Adventures of a Curious Mind

Design Patterns - Java

2017-01-13T16:29:00.000-06:00

Derek Banas created a great simple video quickly describing Design Patterns. Here is the link - https://youtu.be/vNHpsC5ng_E

I am going to text type out the principles discussed below.

What is inheritance?

What do the classes have in common?
Abstract out the features
Override or extend methods that don't work
"is a" relationship

class Animal{
    private String name;
    private double height;
    private int weight;

    public void setName(String newName){
name = newName;
    }
}

class Dog extends Animal{
    public void digHole(String newName){
System.out.println("Hole dug");
    }
}

Fields and methods are already defined when you extend the super class (aka "parent class")
You define only the changes

What is main for?

main creates the objects and then they interact

public static void main(String[] args){
Dog grover = new Dog();
grover.setName("Grover");
grover.name = "Grover"; //do not do this!!! (this gets rid of encapsulation)
}

What is encapsulation?

Allows you do to data hiding
This is done through getters / setters

class Dog extends Animal{
     String name;
    double height;
    int weight;

     public void setWeight(int newWeight){
if(newWeight > 0){
            weight= newWeight;
        }
        else{
           //throw error
        }
    }}

How to hide the data?

Fields (Instance variables) are private
Getters / setters are public

class Dog extends Animal{
     private String name;
     private double height;
     private int weight;

     public void setName(String newName){
name = newName;
    }

public String getName(String newName){
return name;
}
}

Instance & Local Variables?

Fields (Instance variables) are private

Declared in the class

Local variables are declared in a method

class Dog extends Animal{
     private int weight;   // field

     public double getGrams(){
   double gramMult = 453.59; // local variable
       return gramMult * weight;
    }
}

Is A?Versus has A?

Is A? Helps you decide if a class should extend another

Is a Dog an Animal?
Is a Dog a Cat?

Has A? Helps you decide if something is a field

Dog has a height

When to use Inheritance?

The subclass 'is a' superclass; ex) dog 'is an' animal
When a sublcass needs moth of the methods in the superclass

Almost every method in Animal is used in Dog

Don't: Use inheritance just to reuse code, or they dont have a is a relationship

-------------------------------------
Code: (also found here - http://www.newthinktank.com/2012/08/design-patterns-video-tutorial/)

Animal.java

public class Animal {
 
 private String name;
 private double height;
 private int weight;
 private String favFood;
 private double speed;
 private String sound;
 
 public void setName(String newName){ name = newName; }
 public String getName(){ return name; }
 
 public void setHeight(double newHeight){ height = newHeight; }
 public double getHeight(){ return height; }
 
 public void setWeight(int newWeight){ 
  if (newWeight > 0){
   weight = newWeight; 
  } else {
   System.out.println("Weight must be bigger than 0");
  }
 }
 public double getWeight(){ return weight; }
 
 public void setFavFood(String newFavFood){ favFood = newFavFood; }
 public String getFavFood(){ return favFood; }
 
 public void setSpeed(double newSpeed){ speed = newSpeed; }
 public double getSpeed(){ return speed; }
 
 public void setSound(String newSound){ sound = newSound; }
 public String getSound(){ return sound; }
 
 // A private method can only be accessed by other public methods
 // that are in the same class
 
 private void bePrivate(){
  System.out.println("I'm a private method");
 }
 
 public static void main(String[] args){
  
  Animal dog = new Animal();
  
  dog.setName("Grover");
  
  System.out.println(dog.getName());
  
 }
 
}

Dog.java

public class Dog extends Animal{
 
 public void digHole(){
  
  System.out.println("Dug a hole");
  
 }
 
 public void changeVar(int randNum){
  
  randNum = 12;
  
  System.out.println("randNum in method value: " + randNum);
  
 }
 
 
 /* This private method can only be accessed through using other 
  * methods in the class */
 
 private void bePrivate(){
  System.out.println("In a private method");
 } 
 
 public void accessPrivate(){
  bePrivate();
 }
 
 // The constructor initializes all objects
 
 public Dog(){
  
  // Executes the parents constructor
  // Every class has a constructor whether you make it or not
  
  super();
  
  // Sets bark for all Dog objects by default
  
  setSound("Bark");
  
 }
 
}

Cat.java

public class Cat extends Animal{
 
 // The constructor initializes all objects
 
 public Cat(){
  
  // Executes the parents constructor
  // Every class has a constructor whether you make it or not
  
  super();
  
  // Sets bark for all Dog objects by default
  
  setSound("Meow");
  
 }
 
 // If you want to make sure a method isn't overridden mark it as Final
 
 final void attack(){
  // Do stuff that can never change
 }
 
 // A field marked with final can't be changed
 
 public static final double FAVNUMBER = 3.14;
 
 // A class labeled as final can't be extended
 
}

WorkWithAnimals.java

public class WorkWithAnimals{
 
 int justANum = 10;
 
 public static void main(String[] args){
  
  Dog fido = new Dog();
  
  fido.setName("Fido");
  System.out.println(fido.getName());
  
  fido.digHole();
  
  fido.setWeight(-1);
  
  // Everything is pass by value
  // The original is not effected by changes in methods
  
  int randNum = 10;
  fido.changeVar(randNum);
  
  System.out.println("randNum after method call: " + randNum);
  
  // Objects are passed by reference to the original object
  // Changes in methods do effect the object
  
  changeObjectName(fido);
  
  System.out.println("Dog name after method call: " + fido.getName());
  
  System.out.println("Animal Sound: " + fido.getSound());
  
  // Create a Dog and Cat object with the super class
  // but the Dog and Cat reference type
  
  Animal doggy = new Dog();
  Animal kitty = new Cat();
  
  System.out.println("Doggy says: " + doggy.getSound());
  System.out.println("Kitty says: " + kitty.getSound() + "\n");
  
  // Now you can make arrays of Animals and everything just works
  
  Animal[] animals = new Animal[4];
  animals[0] = doggy;
  animals[1] = kitty;
  
  System.out.println("Doggy says: " +animals[0].getSound());
  System.out.println("Kitty says: " +animals[1].getSound() + "\n");
  
  // Sends Animal objects for processing in a method
  
  speakAnimal(doggy);
  
  // Polymorphism allows you to write methods that don't need to 
  // change if new subclasses are created.
  
  // You can't reference methods, or fields that aren't in Animal
  // if you do, you'll have to cast to the required object
  
  ((Dog) doggy).digHole();
  
  // You can't use non-static variables or methods in a static function
  
  // System.out.println(justANum);
  
  // sayHello();
  
  // You can't call a private method even if you define it in
  // the subclass
  
  // fido.bePrivate();
  
  // You can execute a private method by using another public
  // method in the class
  
  fido.accessPrivate();
  
  // Creating a Giraffe from an abstract class
  
  Giraffe giraffe = new Giraffe();
  
  giraffe.setName("Frank");
  
  System.out.println(giraffe.getName());
  
 }
 
 // Any methods that are in a class and not tied to an object must
 // be labeled static. Every object created by this class will
 // share just one static method
 
 public static void changeObjectName(Dog fido){
  
  fido.setName("Marcus");
  
 }
 
 // Receives Animal objects and makes them speak
 
 public static void speakAnimal(Animal randAnimal){
  
  System.out.println("Animal says: " + randAnimal.getSound());
  
 }
 
 // This is a non-static method used to demonstrate that you can't
 // call a non-static method inside a static method
 
 public void sayHello(){
  
  System.out.println("Hello");
  
 }
 
}

Best Java Interview Review I've found yet! And SOAP vs REST.

2016-03-22T08:29:00.000-05:00

http://www.tutorialspoint.com/java/java_interview_questions.htm

------------

SOAP vs REST - http://spf13.com/post/soap-vs-rest

Someone asked me a question today “Why would anyone choose SOAP (Simple Object Access Protocol) instead of REST (Representational State Transfer)?” My response: “The general rule of thumb I’ve always heard is ‘Unless you have a definitive reason to use SOAP use REST’”. He asked “what’s one reason?” I thought about it for a minute and honestly answered that I haven’t ever come across a reason. My background is building great internet companies.
While he seemed satisfied, I wasn’t very happy with that answer, I did some homework and here’s my summary on REST versus SOAP, the difference between SOAP and REST and why anyone would choose SOAP. As usual, with competing technologies both have value, the challenge is to know when to use each one (spoiler: luckily the answer is almost always REST).
I’m clearly boiling down a somewhat so please don’t flame me for simplifying things, but feel free to provide any corrections you feel are necessary.

Definitions

REST

RESTs sweet spot is when you are exposing a public API over the internet to handle CRUD operations on data. REST is focused on accessing named resources through a single consistent interface.

SOAP

SOAP brings it’s own protocol and focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, each implement some business logic through different interfaces.
Though SOAP is commonly referred to as “web services” this is a misnomer. SOAP has very little if anything to do with the Web. REST provides true “Web services” based on URIs and HTTP.
By way of illustration here are few calls and their appropriate home with commentary.

getUser(User);

This is a rest operation as you are accessing a resource (data).

switchCategory(User, OldCategory, NewCategory)

This is a SOAP operation as you are performing an operation.
Yes, either could be done in either SOAP or REST. The purpose is to illustrate the conceptual difference.

Why REST?

Here are a few reasons why REST is almost always the right answer.
Since REST uses standard HTTP it is much simpler in just about ever way. Creating clients, developing APIs, the documentation is much easier to understand and there aren’t very many things that REST doesn’t do easier/better than SOAP.
REST permits many different data formats where as SOAP only permits XML. While this may seem like it adds complexity to REST because you need to handle multiple formats, in my experience it has actually been quite beneficial. JSON usually is a better fit for data and parses much faster. REST allows better support for browser clients due to it’s support for JSON.
REST has better performance and scalability. REST reads can be cached, SOAP based reads cannot be cached.
It’s a bad argument (by authority), but it’s worth mentioning that Yahoo uses REST for all their services including Flickr and del.ici.ous. Amazon and Ebay provide both though Amazon’s internal usage is nearly all REST source. Google used to provide only SOAP for all their services, but in 2006 they deprecated in favor of REST source. It’s interesting how there has been an internal battle between rest vs soap at amazon. For the most part REST dominates their architecture for web services.

Why SOAP?

Here are a few reasons you may want to use SOAP.

WS-Security

While SOAP supports SSL (just like REST) it also supports WS-Security which adds some enterprise security features. Supports identity through intermediaries, not just point to point (SSL). It also provides a standard implementation of data integrity and data privacy. Calling it “Enterprise” isn’t to say it’s more secure, it simply supports some security tools that typical internet services have no need for, in fact they are really only needed in a few “enterprise” scenarios.

WS-AtomicTransaction

Need ACID Transactions over a service, you’re going to need SOAP. While REST supports transactions, it isn’t as comprehensive and isn’t ACID compliant. Fortunately ACID transactions almost never make sense over the internet. REST is limited by HTTP itself which can’t provide two-phase commit across distributed transactional resources, but SOAP can. Internet apps generally don’t need this level of transactional reliability, enterprise apps sometimes do.

WS-ReliableMessaging

Rest doesn’t have a standard messaging system and expects clients to deal with communication failures by retrying. SOAP has successful/retry logic built in and provides end-to-end reliability even through SOAP intermediaries.

Summary

In Summary, SOAP is clearly useful, and important. For instance, if I was writing an iPhone application to interface with my bank I would definitely need to use SOAP. All three features above are required for banking transactions. For example, if I was transferring money from one account to the other, I would need to be certain that it completed. Retrying it could be catastrophic if it succeed the first time, but the response failed.

Embedded / Firmware Interview Review

2016-03-11T08:49:00.004-06:00

Today I have an embedded / firmware interview so gathering resources to review. Here are a few websites that I found:

Below I'll put some information I found useful.

Preprocessor

1. Using the #define statement, how would you declare a manifest constant that returns the number of seconds in a year? Disregard leap years in your answer.
#define SECONDS_PER_YEAR (60UL * 60UL * 24UL * 365UL)

I’m looking for several things here:
(a)    Basic knowledge of the #define syntax (i.e. no semi-colon at the end, the need to parenthesize etc.).
(b)    A good choice of name, with capitalization and underscores.
(c)    An understanding that the pre-processor will evaluate constant expressions for you. Thus, it is clearer, and penalty free to spell out how you are calculating the number of seconds in a year, rather than actually doing the calculation yourself.
(d)    A realization that the expression will overflow an integer argument on a 16 bit machine – hence the need for the L, telling the compiler to treat the expression as a Long.
(e)    As a bonus, if you modified the expression with a UL (indicating unsigned long), then you are off to a great start because you are showing that you are mindful of the perils of signed and unsigned types – and remember, first impressions count!

2. Write the ‘standard’ MIN macro. That is, a macro that takes two arguments and returns the smaller of the two arguments.
#define MIN(A,B)       ((A) <= (B) ? (A) : (B))

The purpose of this question is to test the following:
(a)    Basic knowledge of the #define directive as used in macros. This is important, because until the inline operator becomes part of standard C, macros are the only portable way of generating inline code. Inline code is often necessary in embedded systems in order to achieve the required performance level.
(b)    Knowledge of the ternary conditional operator. This exists in C because it allows the compiler to potentially produce more optimal code than an if-then-else sequence. Given that performance is normally an issue in embedded systems, knowledge and use of this construct is important.
(c)    Understanding of the need to very carefully parenthesize arguments to macros.
(d)    I also use this question to start a discussion on the side effects of macros, e.g. what happens when you write code such as :
least = MIN(*p++, b);
3. What is the purpose of the preprocessor directive #error?
Either you know the answer to this, or you don’t. If you don’t, then see reference 1. This question is very useful for differentiating between normal folks and the nerds. It’s only the nerds that actually read the appendices of C textbooks that find out about such things. Of course, if you aren’t looking for a nerd, the candidate better hope she doesn’t know the answer.

Infinite Loops

4. Infinite loops often arise in embedded systems. How does one code an infinite loop in C?
There are several solutions to this question. My preferred solution is:
while(1)
{
…
}
Another common construct is:
for(;;)
{
…
}
Personally, I dislike this construct because the syntax doesn’t exactly spell out what is going on. Thus, if a candidate gives this as a solution, I’ll use it as an opportunity to explore their rationale for doing so. If their answer is basically – ‘I was taught to do it this way and I have never thought about it since’ – then it tells me something (bad) about them. Conversely, if they state that it’s the K&R preferred method and the only way to get an infinite loop passed Lint, then they score bonus points.
A third solution is to use a goto:
Loop:
…
goto Loop;
Candidates that propose this are either assembly language programmers (which is probably good), or else they are closet BASIC / FORTRAN programmers looking to get into a new field.

Data declarations

5. Using the variable a, write down definitions for the following:
(a) An integer
(b) A pointer to an integer
(c) A pointer to a pointer to an integer
(d) An array of ten integers
(e) An array of ten pointers to integers
(f) A pointer to an array of ten integers
(g) A pointer to a function that takes an integer as an argument and returns an integer
(h)    An array of ten pointers to functions that take an integer argument and return an integer.
The answers are:
(a)    int a;                 // An integer
(b)    int *a;               // A pointer to an integer
(c)    int **a;             // A pointer to a pointer to an integer
(d)    int a[10];          // An array of 10 integers
(e)    int *a[10];        // An array of 10 pointers to integers
(f)     int (*a)[10];     // A pointer to an array of 10 integers
(g)    int (*a)(int);     // A pointer to a function a that takes an integer argument and returns an integer
(h)    int (*a[10])(int); // An array of 10 pointers to functions that take an integer argument and return an integer
People often claim that a couple of these are the sorts of thing that one looks up in textbooks – and I agree. While writing this article, I consulted textbooks to ensure the syntax was correct. However, I expect to be asked this question (or something close to it) when in an interview situation. Consequently, I make sure I know the answers – at least for the few hours of the interview. Candidates that don’t know the answers (or at least most of them) are simply unprepared for the interview. If they can’t be prepared for the interview, what will they be prepared for?

Static

6. What are the uses of the keyword static?
This simple question is rarely answered completely. Static has three distinct uses in C:
(a)    A variable declared static within the body of a function maintains its value between function invocations.
(b)    A variable declared static within a module[1], (but outside the body of a function) is accessible by all functions within that module. It is not accessible by functions within any other module. That is, it is a localized global.
(c)    Functions declared static within a module may only be called by other functions within that module. That is, the scope of the function is localized to the module within which it is declared.
Most candidates get the first part correct. A reasonable number get the second part correct, while a pitiful number understand answer (c). This is a serious weakness in a candidate, since they obviously do not understand the importance and benefits of localizing the scope of both data and code.

Const

7. What does the keyword const mean?
As soon as the interviewee says ‘const means constant’, I know I’m dealing with an amateur. Dan Saks has exhaustively covered const in the last year, such that every reader of ESP should be extremely familiar with what const can and cannot do for you. If you haven’t been reading that column, suffice it to say that const means “read-only”. Although this answer doesn’t really do the subject justice, I’d accept it as a correct answer. (If you want the detailed answer, then read Saks’ columns – carefully!).
If the candidate gets the answer correct, then I’ll ask him these supplemental questions:
What do the following incomplete[2] declarations mean?
const int a;
int const a;
const int *a;
int * const a;
int const * a const;
The first two mean the same thing, namely a is a const (read-only) integer. The third means a is a pointer to a const integer (i.e., the integer isn’t modifiable, but the pointer is). The fourth declares a to be a const pointer to an integer (i.e., the integer pointed to by a is modifiable, but the pointer is not). The final declaration declares a to be a const pointer to a const integer (i.e., neither the integer pointed to by a, nor the pointer itself may be modified).
If the candidate correctly answers these questions, I’ll be impressed.
Incidentally, one might wonder why I put so much emphasis on const, since it is very easy to write a correctly functioning program without ever using it. There are several reasons:
(a)    The use of const conveys some very useful information to someone reading your code. In effect, declaring a parameter const tells the user about its intended usage. If you spend a lot of time cleaning up the mess left by other people, then you’ll quickly learn to appreciate this extra piece of information. (Of course, programmers that use const, rarely leave a mess for others to clean up…)
(b)    const has the potential for generating tighter code by giving the optimizer some additional information.
(c)    Code that uses const liberally is inherently protected by the compiler against inadvertent coding constructs that result in parameters being changed that should not be. In short, they tend to have fewer bugs.

Volatile
8. What does the keyword volatile mean? Give three different examples of its use.
A volatile variable is one that can change unexpectedly. Consequently, the compiler can make no assumptions about the value of the variable. In particular, the optimizer must be careful to reload the variable every time it is used instead of holding a copy in a register. Examples of volatile variables are:
(a)    Hardware registers in peripherals (e.g., status registers)
(b)    Non-stack variables referenced within an interrupt service routine.
(c)    Variables shared by multiple tasks in a multi-threaded application.
If a candidate does not know the answer to this question, they aren’t hired. I consider this the most fundamental question that distinguishes between a ‘C programmer’ and an ‘embedded systems programmer’. Embedded folks deal with hardware, interrupts, RTOSes, and the like. All of these require volatile variables. Failure to understand the concept of volatile will lead to disaster.
On the (dubious) assumption that the interviewee gets this question correct, I like to probe a little deeper, to see if they really understand the full significance of volatile. In particular, I’ll ask them the following:
(a) Can a parameter be both const and volatile? Explain your answer.
(b) Can a pointer be volatile? Explain your answer.
(c) What is wrong with the following function?:
int square(volatile int *ptr)
{
return *ptr * *ptr;
}

The answers are as follows:
(a)    Yes. An example is a read only status register. It is volatile because it can change unexpectedly. It is const because the program should not attempt to modify it.
(b)    Yes. Although this is not very common. An example is when an interrupt service routine modifies a pointer to a buffer.
(c)    This one is wicked. The intent of the code is to return the square of the value pointed to by *ptr. However, since *ptr points to a volatile parameter, the compiler will generate code that looks something like this:
int square(volatile int *ptr)
{
int a,b;
a = *ptr;
b = *ptr;
return a * b;
}
Since it is possible for the value of *ptr to change unexpectedly, it is possible for a and b to be different. Consequently, this code could return a number that is not a square! The correct way to code this is:
long square(volatile int *ptr)
{
int a;
a = *ptr;
return a * a;
}

Bit Manipulation

9. Embedded systems always require the user to manipulate bits in registers or variables. Given an integer variable a, write two code fragments. The first should set bit 3 of a. The second should clear bit 3 of a. In both cases, the remaining bits should be unmodified.
These are the three basic responses to this question:
(a) No idea. The interviewee cannot have done any embedded systems work.
(b) Use bit fields. Bit fields are right up there with trigraphs as the most brain-dead portion of C. Bit fields are inherently non-portable across compilers, and as such guarantee that your code is not reusable. I recently had the misfortune to look at a driver written by Infineon for one of their more complex communications chip. It used bit fields, and was completely useless because my compiler implemented the bit fields the other way around. The moral – never let a non-embedded person anywhere near a real piece of hardware![3]
(c) Use #defines and bit masks. This is a highly portable method, and is the one that should be used. My optimal solution to this problem would be:
#define BIT3 (0x1 << 3)
static int a;
void set_bit3(void) {
a |= BIT3;
}
void clear_bit3(void) {
a &= ~BIT3;
}
Some people prefer to define a mask, together with manifest constants for the set & clear values. This is also acceptable. The important elements that I’m looking for are the use of manifest constants, together with the |= and &= ~ constructs.

Accessing fixed memory locations

10. Embedded systems are often characterized by requiring the programmer to access a specific memory location. On a certain project it is required to set an integer variable at the absolute address 0x67a9 to the value 0xaa55. The compiler is a pure ANSI compiler. Write code to accomplish this task.
This problem tests whether you know that it is legal to typecast an integer to a pointer in order to access an absolute location. The exact syntax varies depending upon one’s style. However, I would typically be looking for something like this:
int *ptr;
ptr = (int *)0x67a9;
*ptr = 0xaa55;
A more obfuscated approach is:
*(int * const)(0x67a9) = 0xaa55;
Even if your taste runs more to the second solution, I suggest the first solution when you are in an interview situation.

Interrupts

11. Interrupts are an important part of embedded systems. Consequently, many compiler vendors offer an extension to standard C to support interrupts. Typically, this new key word is __interrupt. The following code uses __interrupt to define an interrupt service routine. Comment on the code.
__interrupt double compute_area(double radius) {
{
double area = PI * radius * radius;
printf(“\nArea = %f”, area);
return area;
}
This function has so much wrong with it, it’s almost tough to know where to start.
(a)    Interrupt service routines cannot return a value. If you don’t understand this, then you aren’t hired.
(b)    ISR’s cannot be passed parameters. See item (a) for your employment prospects if you missed this.
(c)    On many processors / compilers, floating point operations are not necessarily re-entrant. In some cases one needs to stack additional registers, in other cases, one simply cannot do floating point in an ISR. Furthermore, given that a general rule of thumb is that ISRs should be short and sweet, one wonders about the wisdom of doing floating point math here.
(d)    In a similar vein to point (c), printf() often has problems with reentrancy and performance. If you missed points (c) & (d) then I wouldn’t be too hard on you. Needless to say, if you got these two points, then your employment prospects are looking better and better.

Code Examples

12. What does the following code output and why?
void foo(void)
{
unsigned int a = 6;
int b = -20;
(a+b > 6) ? puts(“> 6”) : puts(“<= 6”);
}
This question tests whether you understand the integer promotion rules in C – an area that I find is very poorly understood by many developers. Anyway, the answer is that this outputs “> 6”. The reason for this is that expressions involving signed and unsigned types have all operands promoted to unsigned types. Thus –20 becomes a very large positive integer and the expression evaluates to greater than 6. This is a very important point in embedded systems where unsigned data types should be used frequently (see reference 2). If you get this one wrong, then you are perilously close to not being hired.
13. Comment on the following code fragment?
unsigned int zero = 0;
unsigned int compzero = 0xFFFF; /*1’s complement of zero */
On machines where an int is not 16 bits, this will be incorrect. It should be coded:
unsigned int compzero = ~0;
This question really gets to whether the candidate understands the importance of word length on a computer. In my experience, good embedded programmers are critically aware of the underlying hardware and its limitations, whereas computer programmers tend to dismiss the hardware as a necessary annoyance.
By this stage, candidates are either completely demoralized – or they are on a roll and having a good time. If it is obvious that the candidate isn’t very good, then the test is terminated at this point. However, if the candidate is doing well, then I throw in these supplemental questions. These questions are hard, and I expect that only the very best candidates will do well on them. In posing these questions, I’m looking more at the way the candidate tackles the problems, rather than the answers. Anyway, have fun…

Dynamic memory allocation.
14. Although not as common as in non-embedded computers, embedded systems still do dynamically allocate memory from the heap. What are the problems with dynamic memory allocation in embedded systems?
Here, I expect the user to mention memory fragmentation, problems with garbage collection, variable execution time, etc. This topic has been covered extensively in ESP, mainly by Plauger. His explanations are far more insightful than anything I could offer here, so go and read those back issues! Having lulled the candidate into a sense of false security, I then offer up this tidbit:
What does the following code fragment output and why?
char *ptr;
if ((ptr = (char *)malloc(0)) == NULL) {
puts(“Got a null pointer”);
}
else {
puts(“Got a valid pointer”);
}
This is a fun question. I stumbled across this only recently, when a colleague of mine inadvertently passed a value of 0 to malloc, and got back a valid pointer! After doing some digging, I discovered that the result of malloc(0) is implementation defined, so that the correct answer is ‘it depends’. I use this to start a discussion on what the interviewee thinks is the correct thing for malloc to do. Getting the right answer here is nowhere near as important as the way you approach the problem and the rationale for your decision.

Typedef

15. Typedef is frequently used in C to declare synonyms for pre-existing data types. It is also possible to use the preprocessor to do something similar. For instance, consider the following code fragment:

#define dPS struct s *
typedef struct s * tPS;

The intent in both cases is to define dPS and tPS to be pointers to structure s. Which method (if any) is preferred and why?
This is a very subtle question, and anyone that gets it right (for the right reason) is to be congratulated or condemned (“get a life” springs to mind). The answer is the typedef is preferred. Consider the declarations:
dPS p1,p2;
tPS p3,p4;
The first expands to
struct s * p1, p2;
which defines p1 to be a pointer to the structure and p2 to be an actual structure, which is probably not what you wanted. The second example correctly defines p3 & p4 to be pointers.

Obfuscated syntax

16. C allows some appalling constructs. Is this construct legal, and if so what does this code do?
int a = 5, b = 7, c;
c = a+++b;
This question is intended to be a lighthearted end to the quiz, as, believe it or not, this is perfectly legal syntax. The question is how does the compiler treat it? Those poor compiler writers actually debated this issue, and came up with the “maximum munch” rule, which stipulates that the compiler should bite off as big a (legal) chunk as it can. Hence, this code is treated as:
c = a++ + b;
Thus, after this code is executed, a = 6, b = 7 & c = 12;
If you knew the answer, or guessed correctly – then well done. If you didn’t know the answer then I would not consider this to be a problem. I find the biggest benefit of this question is that it is very good for stimulating questions on coding styles, the value of code reviews and the benefits of using lint.
Well folks, there you have it. That was my version of the C test. I hope you had as much fun doing it as I had writing it. If you think the test is a good test, then by all means use it in your recruitment. Who knows, I may get lucky in a year or two and end up being on the receiving end of my own work.

--------------------------------------------------------------------------------------------------

What is the need for an infinite loop in Embedded systems?

- Infinite Loops are those program constructs where in there is no break statement so as to get out of the loop, it just keeps looping over the statements within the block defined.
Example:

While(Boolean True) OR for(;;);
{
//Code
}

- Embedded systems need infinite loops for repeatedly processing/monitoring the state of the program. One example could be the case of a program state continuously being checked for any exceptional errors that might just occur during run time such as memory outage or divide by zero etc.,
- For e.g. Customer care Telephone systems where in a pre-recorded audio file is played in case the dialer is put on hold..
- Also circuits being responsible for indicating that a particular component is active/alive during its operation by means of LED's.

How does combination of functions reduce memory requirements in embedded systems?

- The amount of code that has to be dealt with is reduced thus easing the overhead and redundancy is eliminated in case if there is anything common among the functions.

- Memory allocation is another aspect that is optimized and it also makes sense to group a set of functions related in some way as one single unit rather than having them to be dispersed in the whole program.

- In case of interactive systems display of menu list and reading in the choices of user's could be encapsulated as a single unit.

A vast majority of High Performance Embedded systems today use RISC architecture why?

- According to the instruction sets used, computers are normally classified into RISC and CISC. RISC stands for 'Reduced Instruction Set Computing' . The design philosophy of RISC architecture is such that only one instruction is performed on each machine cycle thus taking very less time and speeding up when compared to their CISC counterparts.

- Here the use of registers is optimised as most of the memory access operations are limited to store and load operations.

- Fewer and simple addressing modes, and simple instruction formats leads to greater efficiency, optimisation of compilers, re-organisation of code for better throughput in terms of space and time complexities. All these features make it the choice of architecture in majority of the Embedded systems.

- CISC again have their own advantages and they are preferred whenever the performance and compiler simplification are the issues to be taken care of.

Why do we need virtual device drivers when we have physical device drivers?

Device drivers are basically a set of modules/routines so as to handle a device for which a direct way of communication is not possible through the user's application program and these can be thought of as an interface thus keeping the system small providing for minimalistic of additions of code, if any.
Physical device drivers can’t perform all the logical operations needed in a system in cases like IPC, Signals and so on...

The main reason for having virtual device drivers is to mimic the behaviour of certain hardware devices without it actually being present and these could be attributed to the high cost of the devices or the unavailability of such devices.

These basically create an illusion for the users as if they are using the actual hardware and enable them to carryout their simulation results.
Examples could be the use of virtual drivers in case of Network simulators,also the support of virtual device drivers in case a user runs an additional OS in a virtual box kind of a software.

What is the need for DMAC in ES?

- Direct memory access is mainly used to overcome the disadvantages of interrupt and progam controlled I/O.
- DMA modules usually take the control over from the processor and perform the memory operations and this is mainly because to counteract the mismatch in the processing speeds of I/O units and the procesor. This is comparatively faster.
- It is an important part of any embedded systems,and the reason for their use is that they can be used for bursty data transfers instead of single byte approaches.
- It has to wait for the systems resources such as the system bus in case it is already in control of it.

What is Endianness of a system and how do different systems communicate with each other?

- Endianness basically refers to the ordering of the bytes within words or larger bytes of data treated as a single entity.

- When we consider a several bytes of data say for instance 4 bytes of data,XYZQ the lower byte if stored in a Higher address and others in successively decreasing addresses, then it refers to the Big Endian and the vice versa of this refers to Little Endian architecture.

- Intel 80x86 usually follows Little Endian and others like IBM systems follow Big Endian formats.

- If the data is being transmitted care has to be taken so as to know as to which byte,whether the higher or the lower byte is being transmitted.

- Hence a common format prior to communication has to be agreed upon to avoid wrong interpretation/calculations.
- Usually layer modules are written so as to automate these conversion in Operating systems.

How are macros different from inline functions?

- Macros are normally used whenever a set of instructions/tasks have to be repeatedly performed. They are small programs to carryout some predefined actions.

- We normally use the #define directive in case we need to define the values of some constants so in case a change is needed only the value can be changed and is reflected throughout.

#define mul(a,b) (a*b)

- The major disadvantage of macros is that they are not really functions and the usual error checking and stepping through of the code does not occur.

- Inline functions are expanded whenever it is invoked rather than the control going to the place where the function is defined and avoids all the activities such as saving the return address when a jump is performed. Saves time in case of short codes.

inline float add(float a,float b)
{
return a+b;
}

- Inline is just a request to the compiler and it is upto to the compiler whether to substitute the code at the place of invocation or perform a jump based on its performance algorithms.

What could be the reasons for a System to have gone blank and how would you Debug it?

Possible reasons could be:

- PC being overheated.
- Dust having being accumulated all around.
- CPU fans not working properly .
- Faulty power connections.
- Faulty circuit board from where the power is being drawn.
- Support Drivers not having being installed.

Debugging steps which can be taken are:

- Cleaning the system thoroughly and maintaining it in a dust-free environment. Environment that is cool enough and facilitates for easy passage of air should be ideal enough.

- By locating the appropriate support drivers for the system in consideration and having them installed.

Explain interrupt latency and how can we decrease it?

1. Interrupt latency basically refers to the time span an interrupt is generated and it being serviced by an appropriate routine defined, usually the interrupt handler.
2. External signals, some condition in the program or by the occurrence of some event, these could be the reasons for generation of an interrupt.
3. Interrupts can also be masked so as to ignore them even if an event occurs for which a routine has to be executed.
4. Following steps could be followed to reduce the latency
- ISRs being simple and short.
- Interrupts being serviced immediately
- Avoiding those instructions that increase the latency period.
- Also by prioritizing interrupts over threads.
- Avoiding use of inappropriate APIs.

How to create a child process in linux?

- Prototype of the function used to create a child process is pid_t fork(void);
- Fork is the system call that is used to create a child process. It takes no arguments and returns a value of type pid_t.
- If the function succeeds it returns the pid of the child process created to its parent and child receives a zero value indicating its successful creation.
- On failure, a -1 will be returned in the parent's context, no child process will be created, and errno will be set.
- The child process normally performs all its operations in its parents context but each process independently of one nother and also inherits some of the important attributes from it such as UID, current directory, root directory and so on.

EG Chance's Quake Bible

2013-10-20T14:04:00.005-05:00

Introduction

Practice, Practice, Practice. The famous words of Champion Johnathan "Fatal1ty"
Wendel. We've all heard it before, and we all know how important it is to reaching
the highest levels of play, but what about those guys who practice all day every
day and seem to never improve? I'm sure you know who I'm talking about. That
guy who's been playing for the last 4 years and in the 240 hours of game time
he's logged, since the Quake Live beta opened, has barely managed to etch out a
positive record. Well, this article intends to help those players - and any player
ready to patch up holes in their game that prevent them from reaching higher
levels of play. Unlike other articles, you won't find play by play instructions here.
Quake is about choices. From the second you spawn in, every single thing you do
matters. As we'll see more into this guide, even every single thing you think
about doing matters.

This article is structured around insight. Insights are the foundation for your
improvement; the building blocks of your game. They enable you to make the
right choices at the right times. Without them, you can't build a structure strong
enough to carry you into the next level. Remember that in every step forward
there is an often hidden insight holding it in place that you must find in order to
further establish it as your strength. Meaning, if you're playing great - there's a
reason why. You have to find that reason to retain that level of play. If you're
playing miserably, there's a reason why. You have find that reason and stamp it
out.

The following sections primarily contain insights to help you improve your game
on your own, this is the most important thing you can learn. You won't always
have someone to tell you how to play. Irregardless I cover a few key subjects that
should be your primary focus every time you play. Those two subjects are enemy
status and timing. We'll get to them a little later. For now, we need to understand
some principles to keep your head together.

Discipline. (Willing forward the strongest formula)

Create no waste. Discipline is probably the most difficult and synonymously
important strength of a competitor. Discipline is often what separates the
aforementioned soft practice junkies from the hardened veteran masters. The
practice junkie plays, and plays, and plays, but while he does so he'll be thinking
about doing his laundry. Or what about that new episode of Lost? A thousand
superfluous thoughts are floating through his head while he's drunkenly dropping
into the void like a bewildered klutz or missing the easy jump pad rail. Players like
Fatal1ty will tell you, even when you practice you need to focus 100 percent on
every game, the entire game. If you can keep this up for 8 hours a day you're
going to come out with some serious results. If you can do that, by the way, you
may have some kind of gift ;p. There are few people I know that can play more
than a couple hours without reaching "burn out." Don't concern yourself too much
with the quantity however, because the quality is what counts.

So discipline is largely about staying focused, and staying focused has a lot to do
with your emotional state. You can't be getting too angry, excited, or relaxed
when you need to be completing a crucial task like timing red armor or dodging
behind a pillar. An example of the kind of excitement that creates problems is
when that energetic excited feeling takes your mind out of the game. i.e. "I'm
doing so good! That shot was amazing! Wait.. what was the armor time again?"
Herein lies the difference between an amateur and an expert. The expert player
will simply move onto the next frag, perhaps increasing or maintaining the same
level of energy and readiness whenever necessary.

All that matters is that at the very least you're ready to accept and deal with the
current situation, rather than acting on your emotions regarding the current
situation. On the whole, emotional features like excitement will, by nature, lead
to what are called "leaks." Unintentional holes in your game that, despite knowing
what you should have done in a situation, you went ahead and did something
else. Leaks commonly arise from emotion, but they may also come in a more
dangerously subtle package; thoughts. Anytime you have thoughts floating
around that don't pertain to the game at hand you generate leaks. Disciplined
athletes have little to no leaks.

In order to prevent leaks you have to be aware of your current state of mind.
Keeping your mind clear of fog will allow you to take on any and all information
presented to you, and process it in an unbiased, no-nonsense fashion. With a
clear mind, you stay out of your own way and focus on the critical information
you need to make your next move. That is what strong discipline is about and
that is the core purpose of discipline.

Don't think of discipline as a strenuous exercise. A large part of it is making
yourself comfortable with giving it your all and ensuring you're ready to play
irregardless of what might have or could happen inside and outside of the game.
There is an "easy way" to attain a leak-free strong discipline without breaking
your routine down into thousands of meticulous details and then making yourself
remember them all when you need them. This leads us to our next insight.

Presence. (Remaining in the moment to maximize mental efficiency)

Presence is the state of mind (or no-mind) that has no past or future. Without
past and future, you are not wasting your brain cells/neurons on things that do
not currently exist and therefore hold no bearing on you as a player. You are
focused entirely on what is happening, and since what is happening is all there is,
it is therefore all that matters. This is an easy way "cut down" or lean up your
thoughts and become all killer, no filler. In my experience, you are may only
compete at your peak performance when you are committed fully to the present
moment. The ideal way to look at this is; there is no seperation between you and
what is. This "oneness" is commonly referred to by sports analysts as, "the zone."
Disciplined presence means we should be playing the entire game in the moment
as it emerges unto itself.

You don't need to "think" to strafe jump. You just do it, and the more you can
clear up the mental noise in your head while you play - the more your mind will
wrap around the task you're trying to accomplish. The task of discipline is greatly
simplified by just maintaining continual conscious presence. How is this achieved?
Focus on the task at hand, nothing more, nothing less - and not so much on the
task, but the totality of the moment.

Your mind should be like water, ready to adapt perfectly to fit any container.
Concentrate on what is happening, what the situation needs from you, don't think
it out in long-drawn inner dialogue - just be aware of it and allow it to come
through you. Give your mind the space and freedom to gather all the information
you need. Allow yourself to respond to the situation with relentless indifference,
clarity. Through this comes power. This is natural for a lot of athletes but will take
some practice in itself if you're not used to it. It seems like focusing on the "Now"
is common sense, but that all depends on how aware you are of your straying
thoughts and emotions. There's not much more that I can say about this, you
either get it or you don't. If you don't, just keep playing with a clear head and
always focus. Eventually you'll figure out how to find your "zone." When you do,
recognize the Presence and understand that it is an enormously beneficial ability
which can become absolutely pivitol to your success as a player.

Alright, so. Now we know we need discipline to continually bring our best forward
so we can call on our abilities at will, and we know how to stay in the moment so
we can be efficient with our mental resources. The line between beast and newbie
doesn't stop at staying focused and cognatively present the entire time, you have
to be focused on the right things. Now, what exactly are these "right things" I
keep mentioning, the "important stuff"? What should I concentrate on while I
play?

Opponent Awareness/Enemy Status. (Mastering the raw data.)

Whether you're playing Duel, Team Deathmatch, Clan Arena, Free for All, or even
Counter-Strike for that matter - your awareness of the enemies status is huge.
This is the part of the game that provides you with the information to make
almost all of your decisions useful. I come from a Duel background, so for the
most part I will explain this from a singular, one-player perspective rather than
the plural, team-oriented perspective, but the same nonetheless applies to either
mode.

Your opponent has XXX health and armor (at maximum totalling up to 400), he is
standing X,Y,Z on the map, with X weapons, and X ammo. The opponent is also
moving at XXX units per second. These variables are life and death in the arena.
The ability to contain this information accurately within your consciousness is the
apex of your game. I can't stress this enough because when it comes down to
winning or losing a frag - the most common thing a player does is --misread the
situation and--- mistake some other feature for the reason it happened.

For example: Player B goes through a doorway expecting Player A to have 25
health, when really Player A has 125 because he just got the mega health. When
Player B gets killed after landing a few beads of shaft he gets mad and blames his
aim for not doing enough damage. The anger itself is an issue, but we'll get to
that later. The misjudgment of enemy status is by a landslide the most common
mistake players make, and if not immediately corrected here it has the potential
to just domino.

Any time a gap occurs in our intellect we immediately fill it with the most easily
accessibly and most seemingly obvious reason, and if there is no obvious
reason... we invent one! Creating a solution to fill the gap works well on a short
term scale to alleviate a problem with the best solution we can come up with off
hand, but eventually if the player leaves it unchecked his game's foundation is
liable to become almost superstitious. Many times rather than filling the gaps with
a logical guess to what may have happened players fill it with any answer that
most conveniently protects their ego. Anger is likely indicative of the player trying
to defend his sense of strength that he feels he is losing by being punished.
Players that get stuck in ego will perpetually blame some inauspicious aspect of
the game, continue letting problems chain together by answering them
baselessly, and thus continue to be on the receiving end of the next fragger.

The only way out of this is being honest with yourself and accepting the reality of
the situation, which, I will tell you on the bright side is that you simply did not
accurately read the information you were given. Why is that on the bright side?
Because you no longer have your superstitions like "I just suck" to blame, you
have real, tangible reasoning to tell you what went wrong, and how exactly to
deal with it. We are all human, we all make mistakes. We need to remind
ourselves that these mistakes can either bear fruit, or drag us to hell, depending
on whether we accept our equality and subsequent mortality, or cling to ego and
think somehow we deserve better or worse without first understanding more. It's
the questions we can not answer that cause our suffering should we find
ourselves in a situation where we are struggling.

Once you have accurate awareness of the enemy's status, this is where the Art of
War comes in. (<3 Sun Tzu) Now you can constantly balance your status against
the enemy status, and move accordingly. If you have the advantage, you attack.
At the disadvantage, you wait for your opponent to make a mistake or you retreat
in order to gain more resources than your opponent.

What about when your back is against the wall and you can't retreat? You're out
of luck. The best way out of any sticky situation is to not get stuck there in the
first place. If you're already in this situation you're forced rely on a miracle shot,
opponent choke, luck, or some insight into your opponents fallibility to survive.
This is the last thing you want to do. Good players will attempt to force you into
this situation all game long. There's never a time when they want you to be
prepared.

You always hear about successful athletes and gamers "visualizing" their success.
I promise you they aren't visualizing having 2 health and hitting 5 consecutive
grenades for the win. They're seeing kills unfold realistically and effortlessly in
their minds eye. Studies have shown visualization helps immensely in improving
task completion. In fact, it's been shown that you can actually gain muscle by
merely thinking about lifting weights. Try and keep your opponent contained in
your minds eye throughout the game. And you don't just want to think about
where they are, you want to literally contain them by limiting how they can
expand around the map.

The majority of the learning curve in any game comes from getting yourself into
the right situations. The more experienced you are, the easier it becomes to
make useful choices using the discrepency between your enemies status and your
own, and the more meaningful every move you make becomes. I said it earlier
and I'll say it again. Quake is a game about choices. From the second you spawn
in, every single thing you do or even think about doing matters. Misinformed
decisions lead to death. If you can't figure out immediately why you just lost or
got fragged, go back and examine the replay afterwards. You need to understand
what happened. (Hopefully one day we'll have easy-access demos that display
enemy health, enemies through walls, and item times.)
Enemy status is key, but make sure you're always paying attention to your own
status (and your team if you're in a team mode). You might think you can take on
125 health joe newbie with his spawn shotty - but if you're not healthy enough
and he's in close ducking behind pillars he's gonna drop you like a brick. I'm
always suprising myself how often I go in to attack and look down and realize I've
got 150 armor but only 12 health. It's a given that any time enemy status is
considered, it should be weighed against your and your teammates statuses as
well.

The most difficult thing is gathering this information, and retaining it while
playing. Saying that it's difficult is misleading, however, because this again isn't a
stressful or demanding skill. It can be achieved with ease given time, discipline,
and continual conscious presence. The idea of difficulty is purely psychological
and arises when you resist your current situation or the "time" it takes to
accomplish your desired result.

Other insights reguarding enemy status can include player tendencies. If you've
played a person enough times, or even in your first time playing a guy you can
sometimes pick these up a few minutes in. You can use them to "get inside" your
opponents head, putting damage on them when they're not expecting it - or
taking the RA they always leave up when Mega spawns. Psychology can also play
a role here. If you know your opponent is fatigued, you may be at an advantage.
This isn't something you will want to learn to rely on, but it helps to be aware of it
so when they're feeling peppy next time - you can expect they won't be cutting
you the same slack.

So I know where he is, I know how much health he's got and I'm totally with it.
What else do I need to focus on? We'll discuss just that in the next part.

Resource Timing (Expanding and controlling your advantages)

Resources include items placed around the map that are designed to give you or
your opponent an advantage. In most modes these include weapons, armor,
health, quad, and other powerups. In Quake, it is essential that you time items to
the second. First and foremost you'll be weighing enemy status with your status,
but the ultimate goal of resource management is to effectively eliminate your
opponents ability to gain any significant advantage.

This means timing the most important items while simultaneously preventing
your opponent from getting them. This also means what items you can not time
you need to be mindful of as well. If you know they don't have the Lightning Gun
(LG) but you do, not only will you try to force mid-range fights where you have
the damage advantage, you will also want to prevent them from getting the LG so
you can continue control area's of the map that are best suited for its use. The
same goes for rockets (close range) and rail (long range). As you can see, enemy
status falls in to effect resource status, and vice versa.

In duel, the advantage of the Megahealth and Red Armor are so great that you
want to have each of them timed all game, every game. This is an area where a
lot of players faulter. You can play mindlessly all day long and garner enough
experience to eventually have a pretty solid lock on enemy status, but item
timing is a whole other beast. It takes planning, forethought, careful execution
and extreme intelligence. Experts say you need an IQ somewhere in the 140's at
least. Wait... really? No. Again - this isn't something that requires a lot of stress
or effort. Like everything else it just requires conscious present awareness.
Forethought itself only happens in the present moment. The future holds no
significance. Just because you're timing something does not mean you are
focusing on the future. All timing requires is presence and the ability to add. The
important thing to remember here is to time to the second.

What I often do is simply repeat ":16, :16, :16" in my head and if I have Mega
and RA timed I repeat the RA time too, ":16, :23, :16, :23..." Keep in mind that
its not necessary to time like this if you are good at remembering when it spawns
without it. I generally have trouble timing without repeating the numbers if I
haven't been playing in awhile or I'm distracted (either by physical external things
or just mental noise).

It may also help you to time them out loud. I recall sitting behind Paul "CZM"
Nelson and hearing him chant the spawn times for RA and MH like a quake item
conjurer after he said in the game prior he was having trouble timing. Sometimes
I'll get confused and mix up which items are spawning in which order, especially
when mega is spawning before RA (because mega usually spawns after RA). For
example I'll be repeating ":26, :30, :26, :30" in my head but the item I think is
going to spawn at :26 is actually spawning at :30 and vice versa, so it may be
helpful to remember to emphasise the next coming item in your head first and
foremost.
As we said before, in order to maximize any advantage you gain from picking up
a resource you must time it. Of course this will not be possible with every item,
not only because some items spawn in less than 5 seconds effectively rendering
timing them meaningless, but also because there are often 20+ items per map
and the average human being can only remember around 8 digits at a time.
So why is timing a weakness for so many? Well for starters, many players
experience heavy mental resistance to it, most often labeling it as a "less fun"
aspect of the game. Other people are trapped in the illusion that its too effortful,
and requires too much of their concentration or is beyond their intelligence.
General lack of discipline is, however, the biggest problem. Mental wandering
anyone? Too frustrated or impatient to remember the time? There's your lacking
discipline.

Item status, enemy status, and team status are an interconnected power struggle
where the exact respawn times play a critical role. Megahealth respawns at :XX,
red armor at :XX. You have XXX health+armor... You get the picture. Accuracy
within these categories takes time and determination to master. Along the way,
its a lot of fun. Brilliant plays start to emerge when both players become fully
aware of the enemy status and item times. It's a game with RTS style resource
management and Fighting game reflexes. The overlay of deception and
punctuality unfolds a dynamic and eternally interesting genre of E-Sport. Every
map has a unique architecture, powerup layout and weapon scheme. This sets
the stage for a vast set of gameplay meta-memes and personal meme's just
waiting to be uncovered.

Perhaps in the future I'll write an article laying out the specific meta-strategies
encountered on individual maps, but for now this marks the conclusion of the
"what to do/think about in-game" section. From here, there's a few other things
to consider pre-game and post-game.

Aim (The most overthought skill in Quake.)

If you were to ask the best aimer in the world how he aims so good he would
probably explain the process in a way that would leave you just as well off as if
he told you to tap your heals together and wish for good aim. Indeed, the concept
of "aiming well" is one place where things get a little foggy for us humans to
describe =]. We tend to try to quantify things in order to understand them and
aim is such a dynamic category we are stuck with a lack of general insight here.
But there are a few things that I think play a crucial role in aim.

1. Comfortablility. Firstly, you need to be comfortable with your environment. If
you're not used the height of your chair, size of the monitor, shape of your mouse
etc. you may have trouble aiming just because you'll be encumbered with
discomfort the whole game. Simple ^_^. Next you need a sensitivity you can
stand behind 100 percent. To do this, you need it to meet the demands of the
arena with absolute ease and comfort. This means setting it high enough for
those quick yet important placement shots, and having it low enough to maintain
a steady track.

Warmup is there purely to get a good comfortable feel for your setup and make
your mind comfortable with your sensitivity and the general handling of your
mouse again.

2. Concentration. I've said enough on this already. Presence directly equates to
amazing aim =]

3. Movement. Great movement kills two birds with one stone. You stand where
you need to be to simplify the shot(s) while synonymously avoiding enemy
attacks.

These are really the only three factors of any relevance that I can offer you when
it comes to aiming. A lot of people get borderline superstitious with their aim.
Some will nervously tweak mouse settings, sensitivities, visual configs like they
have obsessive compulsive disorder. Don't be that guy ;p.

Here's a few more tips to make sure you're on the right track.

Stop trying to predict the future. There's a lot of hype in being able to "read" your
opponent. Thats fine, but don't mistake "reading" them for predicting them. You
can not predict what a person will do. Trying to predict player movement in battle
will only lead to poor accuracy and frustration. What you can do is merely read
their movements and this'll be all you need to match them perfectly. So stop
spamming that corner for 10 seconds cause he's already behind you :p. In a
straight up shaft fight you want your crosshair to track the opponent with the
immediacy of a shadow (<3 Bruce Lee), and you can only achieve this through
total presence.

Just like we discussed earlier with enemy status, putting yourself in the right
situation with aim also has an enormous value. You're not going to miss that
jump pad shot when you're 200/200 and have every item in the map on lock. The
reason? Comfortability and simplicity. You're comfortable because you're in the
exact situation you need to be, add that to the fact that the shot is the simplest
shot in the game and probably doesn't even require you to move - and you have
yourself a winner :)

Motivation, Attitude (Pushing the limits)

It's important to keep a healthy morale when you go to play a game. Sometimes
you just aren't motivated. If you're not feeling up to a game, don't play. It takes
discipline just to take a break sometimes. A lot of players think, "Man, I keep
losing because I'm playing bad... I'm playing badly because I don't feel like
playing... but I need to get better so I have to keep playing." This is a vicious
cycle that traps almost every aspiring pro*** at some point. If you find yourself
in that situation you just need to remind yourself that it's the quality that counts.
Taking into account the stress of tournaments, it may all be a bit overwhelming at
times. If you're new to the scene, you might be freaking out months before the
tournament even starts. If you take my previous advice, you know its not smart
to practice when you're stressed because you'll be too emotional to concentrate
or play your best. So how will you get practice if you're purposely not playing
because the pressure is too high? The answer is simple. Do what you can with
what you have, and, you receive what you give.

"Do what you can with what you have." What I mean by this is, you do as much
as you can with what you're given. Whatever that means, whatever situation you
are in. If you're stressed out and you can't seem to calm down, you have may
have no choice but to play through it. You gotta accept that you're just going to
suck while you play. If you can't practice for a solid week before an event, what
can you do about it? Do everything you can but don't resist it psychologically. You
have to bring peace into the game in order to maintain functionality because....
"You receive what you give." Give it nothing, you can expect to receive nothing.
Give it your all, every, single, time-- you're going to get something back. If it's
not enough for you, too bad - give it some more. How is there a choice in the
matter? And don't just give it more- give it better, brighter. Give it lightness,
freedom, joy, enthusiasm. See what you get back. Life is the journey, a beautiful
means through uncertainty. So you start with what you have, and you do what
you can with it. Give it your all, Good luck.

Resolve. (Conscious adaptation)

Alright, so I'm practicing really hard and I'm paying acute attention to everything
thats happening - but I still having troubles with such-and-such problem(s). This
is where resolve comes in. Resolve is my favorite word, it just means so much
(seriously, it has 18 definitions on dictionary.com.) I said at the beginning of this
article that discipline may be the most important aspect of an individuals ability,
to me resolve plays a key just above that. Resolve gives you the ability to take a
step back, and tackle the problem again from a different angle. Or maybe just
tackle it harder this time. Or maybe lets try diving in on it from above. What if we
dug a hole and trapped the problem in a pit of spikes? No, I've got it... we'll use
magnets!... haha

A brilliant player (you know who you are) once told me repeatedly to think
outside the box. I kept thinking to myself, "What does that even mean?" I think
the answer to that question, or any question, is the fruit of resolve. With your
resolve you have ability to adapt, rework, recreate, restore, regenerate, renew.
Resolve is the forge by which the blade of your will is tempered. And like any
great sword, it must be shaped, heated, cooled, and folded thousands of times
before it is perfect - but who is ever perfect?
The end.

I want to remind you that while all these insights are important, and though its
important to gather new knowledge - the core of your concentration while playing
should be on enemy status, and timing. These two components are the basis for
all in-game decision making.

Hopefully this article has given you some knew knowledge or at least a fresh
perspective on things. If you still find yourself getting stuck, try writing stuff
down, you can build a journal or progress report of sorts this way.
It's been fun sharing with you all! Keep at it and together we will improve the
meta game! See you on the interwebs =]

Sound 101

2013-05-12T19:59:00.000-05:00

So today I wanted to purchase new head phones. Just when I got back I was just wanting to confirm the specifications that I used to purchase. Which by the way, I purchased the JVC HA-S600-B from Fry's.

I specifically liked the frequency range of the sound - 8Hz-25KHz. So it had a nice range of bass as well as treble.

Here is a cool website that explained everything that goes on behind sound engineering. - http://www.tech-forums.net/forums/f12/sound-101-a-169733/
-------------

So... you're lookin fer some bumpin speakers eh? Well, heres some tips for you. Headphones can also follow these guidelines!

First of all, wattage isn't everything. Wattage is only the power your feeding to it. Also, especially when looking at 5.1 or 7.1 systems, when the box says "A WHOPPING 100w!", you have to remember... that 100watts is divided 6 ways (5.1) or even 8 ways (7.1). Usually, the sub will get most of the power and the satellites will get a miniscule amount. Higher wattage is good, but not always better. As this is just basic information, I'm not going to get into RMS and Peak power ratings, but researching these two forms of power is DEFINITELY a must when looking at speakers/amps. Also, resistance (ohms) is another thing you may want to dabble into.

------------------

Since wattage isn't everything, what is? Sensitivity!!! Ok... so you spent your hard earned cash on some awesome speakers with 500 watts of power. Freakin sweet eh? You open the box, get everything all set up and you go to press PLAY anxiously waiting for your heart to be resuscitated by the massive 500watts flowing through them speakers. You press play and what you hear is good. Then you take the dive and turn the volume up. "WTF?! I've got these things all the way up and they aren't loud whatsoever!! WHAT BS!!!" Sensitivity my good friend. So what is sensitivity? Well, in most specifications you will see a section called Signal to noise ratio (SNR) or sensitivity. Then you will get a number followed by dB (decibels). Say this number is 50dB (which is horrendous), that means for every one watt of power going in, 50 decibels of sound will come out (if playing white noise at nominal level). Most consumer quality stuff ranges from 70-80's. You really want at least 89dB. Anything above 90 will give you plenty of volume and will use its wattage more efficiently.

------------------

Anything else? DUH! We haven't even scratched the surface! Frequency range!! Frequency range is that weird section of numbers that no one ever understands. (100-20,000hz). What the heck does that mean? Well, hz (hertz) is a measurement of how many times a sound wave cycles in one second. So, the lower the number, the slower the wave. Thusly, the slower the wave, the lower it sounds. The human hearing range is technically 20hz-20,000hz (or 20khz). I consider the USABLE range to be 30hz-18khz Although I can hear 20-20k, people above 25 years old(ranges) can't hear much above 17k due to hearing damage (no matter what you do, it happens when you get older).

A GOOD frequency range is having the first number as low as possible and the second number as high as possible. So, if your speakers have a 75hz-16,000hz (which is not so great) range, if you play anything below or above those numbers, you wont hear it as your speakers can't play it. Chest thumping is normally found around 30-60hz. A good range I like to follow is to keep the first number below 50hz and the high number at least at 18khz (or 18,000hz).

------------------

Digital versus analog! WHAT?! THERE ARE NO SUCH THINGS AS DIGITAL SPEAKERS! NEVER! Speakers are purely an analog mechanism. A speaker consists of a magnet, a voice coil, a spider and a cone (with a dust cap in the middle, which really serves no purpose). Essentially, the speaker vibrates (in AND out) to move molecules which form sound waves. When a description says DIGITAL SPEAKERS, that means it has a digital to analog converter (AD/DA) OR it has a digital decoder built in. Digital connections only transmit information. No audio whatsoever. Just a bunch of ones and zeros.

So now you should have a basic understanding about speakers and headphones. Now, go out and get yourself some GOOD speakers (excluding Bose).

Whats next? Wiring!

Let's say you've got some sweet speakers and a really sweet amp. Rock on eh? Car install, home theater, whatever... wiring it all up goes here! There are a few different ways to wire things up, but first we gotta understand the basics:

Ohms (impedence or resistance)
Wattage
Load
Phase

Let's start with resistance! This can be quite the challenge, but its quite simple. Every speaker has a level of resistance, called impedence. Impedence is measured in what's called Ohm's. Now, we could get crazy and go into Ohm's Law, but theres really no point without going into some advanced stuff. Just so you can see it, here is the Ohm's Law chart:

This is used for figuring Impedence (resistance), wattage, voltage, and current. Simple math as long as you know the information. Anyways, back to resistance. You know how on your amplifier it says it can handle X amount of ohms? Well, thats what is called Load. 8ohms and 4ohms are the most common, but there are components that run even lower than that. How do we figure out load? Well, that all depends on how things are wired up. There are three ways to wire: Series, Parallel, and Series Parallel (I know, scary... don't worry). When hooking up more than one speaker, you have to use one of these wiring methods. Though it may seem obvious, but "black goes to black and red goes to red". These are the positive and negative leads. This gets into phase, which we'll learn a bit later.

Series:

As you can see, there are two 8ohm speakers hooked up. When you wire them in series method, you add the resistance of all of the speakers, and you get your load. In this case, 8+8= 16ohm load. REMEMBER! The higher the resistance, the lower the output. Why? Most amplifiers can handle high loads. The less resistance there is, the more power the speakers will draw from the amp, the more output (and we all know what that means... LOUDER!). The smaller load rating on the amp, the better. If the amp can handle 2 ohms, you better be sure it can give you more than enough power for any application. In the case of the picture above, it won't be very hard at all for the amp to drive those two speakers, but keep in mind that it sure isn't going to get that loud. It may be better to wire it in a different method, such as parallel!

Parallel:

Here we have the same to speakers, but wired differently. When wiring in parallel, you multiply the resistance of all of the speakers, and divide it by the sum of all the resistance of the speakers. This will give you your load rating. Here we have two 8ohm speakers wired in parallel. So, we take 8 * 8 = 64 ---- 64 / 16 = 4 ---- This gives us a load of 4ohms. If we were to hook up this to the same amplifier as we did with series, we would get a much high output since it is drawing much more power from the amp.

Series Parallel

Embedded Systems Interview Review

2013-03-22T14:24:00.000-05:00

Today, I have a few interviews lined up. I want to do well of course, so I thought I would lay out some interview review.

Let's begin!

A really awesome review is linked here- http://www.sanjayahuja.com/Interview%20questions.pdf
--------------
This information came from- http://careerride.com/embedded-systems-interview-questions.aspx

What is the need for an infinite loop in Embedded systems?

Infinite Loops are those program constructs where in there is no break statement so as to get out of the loop, it just keeps looping over the statements within the block defined.
Example:
While(1) {}

OR

for(;;);
{
//Code
}
Embedded systems need infinite loops for repeatedly processing/monitoring the state of the program. One example could be the case of a program state continuously being checked for any exceptional errors that might just occur during run time such as memory outage or divide by zero etc.,

For e.g. Customer care Telephone systems where in a per-recorded audio file is played in case the dialer is put on hold..

Also circuits being responsible for indicating that a particular component is active/alive during its operation by means of LED's.

How does combination of functions reduce memory requirements in embedded systems?

The amount of code that has to be dealt with is reduced thus easing the overhead and redundancy is eliminated in case if there is anything common among the functions.

Memory allocation is another aspect that is optimized and it also makes sense to group a set of functions related in some way as one single unit rather than having them to be dispersed in the whole program.

In case of interactive systems display of menu list and reading in the choices of user's could be encapsulated as a single unit.

A vast majority of High Performance Embedded systems today use RISC architecture why?

According to the instruction sets used, computers are normally classified into RISC and CISC. RISC stands for 'Reduced Instruction Set Computing' .The design philosophy of RISC architecture is such that only one instruction is performed on each machine cycle thus taking very less time and speeding up when compared to their CISC counterparts.

Here the use of registers is optimized as most of the memory access operations are limited to store and load operations.

Fewer and simple addressing modes, and simple instruction formats leads to greater efficiency, optimization of compilers, re-organisation of code for better throughput in terms of space and time complexities. All these features make it the choice of architecture in majority of the Embedded systems.

CISC again have their own advantages and they are preferred whenever the performance and compiler simplification are the issues to be taken care of.

CISC	RISC
Emphasis on hardware	Emphasis on software
Includes multi-clock complex instructions	Single-clock, reduced instruction only
Memory-to-memory: "LOAD" and "STORE" incorporated in instructions	Register to register: "LOAD" and "STORE" are independent instructions
Small code sizes, high cycles per second	Low cycles per second, large code sizes
Transistors used for storing complex instructions	Spends more transistors on memory registers

However, the RISC strategy also brings some very important advantages. Because each instruction requires only one clock cycle to execute, the entire program will execute in approximately the same amount of time as the multi-cycle "MULT" command. These RISC "reduced instructions" require less transistors of hardware space than the complex instructions, leaving more room

The Performance Equation
The following equation is commonly used for expressing a computer's performance ability:

The CISC approach attempts to minimize the number of instructions per program, sacrificing the number of cycles per instruction. RISC does the opposite, reducing the cycles per instruction at the cost of the number of instructions per program.

(above table- http://www-cs-faculty.stanford.edu/~eroberts/courses/soco/projects/risc/risccisc/)

Why do we need virtual device drivers when we have physical device drivers?

Device drivers are basically a set of modules/routines so as to handle a device for which a direct way of communication is not possible through the user's application program and these can be thought of as an interface thus keeping the system small providing for minimalistic of additions of code, if any.
Physical device drivers can’t perform all the logical operations needed in a system in cases like IPC, Signals and so on...
The main reason for having virtual device drivers is to mimic the behaviour of certain hardware devices without it actually being present and these could be attributed to the high cost of the devices or the unavailability of such devices.
These basically create an illusion for the users as if they are using the actual hardware and enable them to carryout their simulation results.
Examples could be the use of virtual drivers in case of Network simulators,also the support of virtual device drivers in case a user runs an additional OS in a virtual box kind of a software.

What is the need for DMAC in ES?

Direct memory access is mainly used to overcome the disadvantages of interrupt and progam controlled I/O.
DMA modules usually take the control over from the processor and perform the memory operations and this is mainly because to counteract the mismatch in the processing speeds of I/O units and the procesor.This is comparatively faster.

It is an important part of any embedded systems,and the reason for their use is that they can be used for bursty data transfers instead of single byte approaches.
It has to wait for the systems resources such as the system bus in case it is already in control of it.

What is Endianness of a system and how do different systems communicate with each other?

Endianness basically refers to the ordering of the bytes within words or larger bytes of data treated as a single entity.
When we consider a several bytes of data say for instance 4 bytes of data,XYZQ the lower byte if stored in a Higher address and others in successively decreasing addresses ,then it refers to the Big Endian and the vice versa of this refers to Little Endian architecture.
Intel 80x86 usually follows Little Endian and others like IBM systems follow Big Endian formats.
If the data is being transmitted care has to be taken so as to know as to which byte,whether the higher or the lower byte is being transmitted.
Hence a common format prior to communication has to be agreed upon to avoid wrong interpretation/calculations.
Usually layer modules are written so as to automate these conversion in Operating systems.

"Little Endian" means that the low-order byte of the number is stored in memory at the lowest address, and the high-order byte at the highest address. (The little end comes first.) For example, a 4 byte LongInt

    Byte3 Byte2 Byte1 Byte0

will be arranged in memory as follows:

    Base Address+0   Byte0
    Base Address+1   Byte1
    Base Address+2   Byte2
    Base Address+3   Byte3

Intel processors (those used in PC's) use "Little Endian" byte order. "Big Endian" means that the high-order byte of the number is stored in memory at the lowest address, and the low-order byte at the highest address. (The big end comes first.) Our LongInt, would then be stored as:

    Base Address+0   Byte3
    Base Address+1   Byte2
    Base Address+2   Byte1
    Base Address+3   Byte0

Motorola processors (those used in Mac's) use "Big Endian" byte order.
^Found from http://people.cs.umass.edu/~verts/cs32/endian.html

How are macros different from inline functions?

Macros are normally used whenever a set of instructions/tasks have to be repeatedly performed. They are small programs to carryout some predefined actions.
We normally use the #define directive in case we need to define the values of some constants so in case a change is needed only the value can be changed and is reflected throughout.
#define mul(a,b) (a*b)
The major disadvantage of macros is that they are not really functions and the usual error checking and stepping through of the code does not occur.
Inline functions are expanded whenever it is invoked rather than the control going to the place where the function is defined and avoids all the activities such as saving the return address when a jump is performed. Saves time in case of short codes.
inline float add(float a,float b)
{
return a+b;
}
Inline is just a request to the compiler and it is upto to the compiler whether to substitute the code at the place of invocation or perform a jump based on its performance algorithms.

What could be the reasons for a System to have gone blank and how would you Debug it?

Possible reasons could be,
- PC being overheated.
- Dust having being accumulated all around.
- CPU fans not working properly .
- Faulty power connections.
- Faulty circuit board from where the power is being drawn.
- Support Drivers not having being installed.

Debugging steps which can be taken are:

- Cleaning the system thoroughly and maintaining it in a dust-free environment.
Environment that is cool enough and facilitates for easy passage of air should be ideal enough.

- By locating the appropriate support drivers for the system in consideration and having them installed.

Explain interrupt latency and how can we decrease it?

Interrupt latency basically refers to the time span an interrupt is generated and it being serviced by an appropriate routine defined.,usually the interrupt handler.
External signals,some condition in the program or by the occurrence of some event,these could be the reasons for generation of an interrupt.
Interrupts can also be masked so as to ignore them even if an event occurs for which a routine has to be executed.
Following steps could be followed to reduce the latency
- isrs being simple and short.
- Interrupts being serviced immediately
- Avoiding those instructions that increase the latency period.
- Also by prioritizing interrupts over threads.
- Avoiding use of inappropriate APIs.

How to create a child process in linux?

Prototype of the function used to create a child process is pid_t fork(void);
Fork is the system call that is used to create a child process. It takes no arguments and returns a value of type pid_t.
If the function succeeds it returns the pid of the child process created to its parent and child receives a zero value indicating its successful creation.
On failure, a -1 will be returned in the parent's context, no child process will be created, and errno will be set
The child process normally performs all its operations in its parents context but each process independently of one another and also inherits some of the important attributes from it such as UID, current directory, root directory and so on.

Significance of watchdog timer in Embedded Systems

Watchdog timer is basically a timing device that is set for predefined time interval and some event should occur during that time interval else the device generates a time out signal.
One application where it is most widely used is when the mobile phone hangs and no activity takes place,in those cases watchdog timer performs a restart of the system and comes to the rescue of the users.
It is used to reset to the original state whenever some inappropriate events take place such as too many commands being given at the same time or other activities that result in malfunctioning of the GUI.It is usually operated by counter devices.

If you buy some RTOS, what are the features you look for in ?

-Deterministic operating system having guaranteed worst-case interrupt latency and context-switch times.
-Documentation providing for the minimum, average, and maximum number of clock cycles required by each system call
-Interrupt response times should be very minute.
-Context switch time should be very low.
-Compatibility with several plugin devices.
- Overall it should be very reliable.

Why is java mostly used in embedded systems?

Java was mainly designed and conceputalised for code that can work on different platforms without any hassles and also for being secure enough so as to not harm or corrupt other modules of code.
Features like exception handling,simple syntax and Automatic Garbage collection all work in its favour as the language for use in ES's.
Also that it is widely used in the form of Java applets makes it very popular confining it to the limits of JVM.It is Dynamic in nature.
Its use is also being exploited in enterprise systems in the form of J2EE ,J2SE
J2ME in case of mobile applications.

Differentiate between mutexes vs semaphores

-Semaphores is a synchronisation tool to overcome the critical section problem.
- A semaphore S is basically an integer variable that apart from initialisation is accesses only through atomic operations such as wait() and signal().
- Semaphore object basically acts as a counter to monitor the number of threads accessing a resource.
- Mutex is also a tool that is used to provide deadlock free mutual exclusion.It protects access to every critical data item.if the data is locked and is in use,it either waits for the thread to finish or awakened to release the lock from its inactive state.

What are the commonly found errors in Embedded Systems?

- Damage of memory devices due to transient current and static discharges.
- Malfunctioning of address lines due to a short in the circuit
- Malfunctioning of Data lines.
- Some memory locations being inaccessible in storage due to garbage or errors.
- Improper insertion of Memory devices into the memory slots
- Faulty control signals.

What is the need for having multibyte data input and output buffers in case of device ports?

It’s normally the case that some devices transfer the output either in a bursty or a sequential manner and also during input entry. If we take the example of keyboards, all the data entered is stored in a buffer and given at a time or one character at a time.
In case of networking there may be several requests to access the same resource and all these are queued in a buffer and serviced in the order they are received
Hence to avoid the input/output units from getting overloaded with requests, we use multibyte buffers.

--------------
The following are basic interview questions for embedded systems - found http://careerride.com/embedded-systems-interview-for-freshers.aspx

What is lst file?

• This file is also called as list file.
• It lists the opcodes ,addresses and errors detected by the assembler.
• List file is produced only when indicated by the user.
• It can be accessed by an editor and displayedon monitor screen or printed.
• Progammer uses this file to find the syntax errors and later fix them.

How is a program executed’ bit by bit’ or’ byte by byte’?

EXAMPLE

ADDRESS	OPCODE	PROGRAM
1 0000		ORG 0H
2 0000	7D25	MOV R5,#25H
3 0002	7F34	MOV R7,#34H
4 0004	2D	ADD A, R5
5 0005		END

• A program is always executed byte by byte.
• Firstly,1st opcode 7D is fetched from location 0000 and then the value 25 is fetched from 0001 .
• 25 is then placed in the register R5 and program counter is incremented to point 0002.
• On execution of opcode 7F, value 34 is copied to register R7.
• Then addition of contents of R5 and accumulater takes place.
• Here all the opcodes are 8 bit forming a byte.

Explain DB.

• DB is called as define byte used as a directive in the assembler.
• It is used to define the 8 bit data in binary ,hexadecimal or decimal formats.
• It is the only directive that can be used to define ASCII strings larger than two characters.
• DB is also used to allocate memory in byte sized chunks.
• The assembler always converts the numbers lnto hexadecimal.

What is EQU?

• EQU is the equate assmbler directive used to define a constant without occupying a memory location.
• It associates a constant value with data label .
• Whenever the label appears in the program ,constant value is subsituted for label.
• Advantage: The constant value occuring at various positions in a program can be changed at once using this directive.
• Syntax: label EQU constant value

How are labels named in assembly language?

• Label name should be unique and must contain alphabetic letters in both uppercase and lowercase.
• 1st letter should always be an alphabetic letter.
• It can also use digits and special characters ?,.,@,_,$.
• Label should not be one of the reserved words in assembly language.
• These labels make the progam much easier to read and maintain.

Are all the bits of flag register used in 8051?

• The flag register also called as the program status word uses only 6 bits.
• The two unused bits are user defineable flags.
• Carry ,auxillary carry ,parity and overflow flags are the conditional flags used in it.
• PSW.1 is a user definable bit and PSW.5 can be used as general purpose bit.
• Rest all flags indicate some or the other condition of an arithematic operation.

Which bit of the flag register is set when output overflows to the sign bit?

• The 2nd bit of the flag register is set when output flows to the sign bit.
• This flag is also called as the overflow flag.
• Here the output of the signed number operation is too large to be accomodated in 7 bits.
• For signed numbers the MSB is used to indicate the whether the number is positive or negative.
• It is only used to detect errors in signed number operations.

Which register bank is used if we use the following instructions
SETB PSW.3 A
SETB PSW.4 B

• Statement A sets 3rd bit of flag register.
• Statement B sets 4th bit of flag register.
• Therefore register bank 3 is initiated .
• It uses memory location 18H to 1FH.
• The register bank is also called as R3.

Issues related to stack and bank 1.

• Bank 1 uses the same RAM space as the stack.
• Stack pointer is incremented or decremented according to the push or pop instruction.
• If the stack pointer is decremented it uses locations 7,6,5… which belongs to register bank 0.
• If a given program uses R1 then stack is provided new memory location.
• The push instruction may also take stack to location 0 i.e.it will run out of space.

Explain JNC.

• It is a command used to jump if no carry occurs after an arithematic operation.
• It is called as jump if no carry( conditional jump instruction).
• Here the carry flag bit in PSW register is used to make decision.
• The processor looks at the carry flag to see if it is raised or not.
• If carry flag is 0 ,CPU fetches instructions from the address of the label.

Write a program to toggle all bits of P1 every 200ms.

                    MOV              A,#55H
AGAIN:       MOV              P1,A
                    ACALL          DELAY
                    CPL               A
                    SJMP            AGAIN

DELAY:
                    MOV              R5,#9
HERE1:     MOV              R4,#242
HERE2:     MOV              R3,#255
HERE3:     DJNZ            R3,HERE3
                    DJNZ            R4,HERE2
                    DJNZ            R5,HERE1
                    RET
• Here the delay produced is 9*255*4MC*90=199,940 micro seconds.
• CPL is used to toggle the bits of P1.
• Short jump is jusd to produce a continuous loop.

Can port 0 be used as input output port?

• Yes, port 0 can be used as input output port.
• Port 0 is an open drain unlike ports 2,3,4.
• To use it as input or output the 10k ohm pull-up resisters are connected to it externally.
• To make port 0 as input port it must be programmed by writing 1 to all bits.
• Example:

MOV A,#0FFH
MOV P0,A

Which 2 ports combine to form the 16 bit address for external memory access?

• Port0 and port2 together form the 16 bit address for external memory.
• Port0 uses pins 32 to 39 of 8051 to give the lower address bits(AD0-AD7)
• Port2 uses pins 21 to 28 of 8051 to give the higher address bits(A8-A15)
• This 16 bit address is used to access external memory if attached.
• When connected to external memory they cannot be used as input output ports.

Can single bit of a port be accessed in 8051?

• Yes,8051 has the capability of accessing only single bit of a port.
• Here only single bit is accessed and rest are unaltered.
• SYNTAX: “SETB X. Y”.
• Here X is the port number and y is the desired bit.
• Example: SETB P1.2

Here the second bit of port 1 is set to 1.

Other than SETB ,CLR are there any single bit instructions ?

• There are total 6 single-bit instructions.
• CPL bit : complement the bit (bit= NOT bit).
• JB bit,target: Jump to target if bit equal to 1.
• JNB bit,target: Jump to target if bit is equal to 0.
• JCB bit,target: Jump to target if bit is equal to 1 and then clear bit.

Review Buck, Boost, LDO, PWM, and FIR vs IIR

2013-01-12T21:28:00.001-06:00

Charis Poag, 1/5/13

The following information was obtained for a company I am applying for (omitted name). One of the Design directors asked me some questions during the interview. So I went ahead and did some research to refresh my mind on their technologies over the weekend.

Power i nformation came from: http://users.ece.utexas.edu/~kwasinski/teaching.html and some from Wikipedia and youtube videos.

Main knowledge of DSP information came from: http://users.ece.utexas.edu/~bevans/courses/realtime/lectures/index.html

a) Buck converters-

A buck converter is a method to "step-down DC to DC converter". Our goal is to have a high efficiency design, ie our lossless objective: Power in = power out, thus Vin*Iin =Vout*Iout -> Vout/Vin = Iin/Iout. The typical buck converter design is shown in the figure below.

Note: the switch is typically a MOSFET,IGBT, or BJT.

Idea: voltage regulation by the inductor--

Also energy stored in an inductor is described as-

The theory of operation is fairly simple, with an inductor and two switches (usually created with a transistor and a diode) which controls the inductor converter. The best way to understand this is to think in terms of the inductor's reluctance to allow a change in current. So when the switch is open (seen in picture below as the "off" position), the current in the circuit is 0 in the beginning. But when the switch is closed, the current begins to increase, but the inductor does not want it to change from 0, so it attempts to fight the increase by dropping the voltage. The voltage drop counters the voltage of the source and reduces the net voltage across the load. Over time, the inductor allows current to increase slowly by decreasing the voltage it drops, thus increasing the net voltage seen by the load. This process causes the inductor to store the energy in the form of a magnetic field.

If the switch is opened before the inductor fully charges (in other words, before it has allowed all current to pass through by reducing its own voltage drop to 0), then there will always be a voltage drop across it. Thus the net voltage seen by the load is always less than the input voltage source. Overtime, the inductor allows the current to decrease gradually, which it does by decreasing the voltage across itself. During this time, the inductor is discharging its stored energy into the rest of the circuit.

If the switch is closed again before the inductor fully discharges, the load will always see a non-zero voltage. The capacitor placed in parallel with the lad helps smooth out this voltage waveform as the inductor charges and discharges each cycle. As seen in the figure below the circuit diagrams.

By keeping the inductor in a state of not fully charging and discharging we are able to create a circuit which lowers the output voltage. This also allows us to control the power efficiency of the circuit. A more in depth discussion of this circuit can be found on Wikipedia or other educational resources which describe the continuous and discontinuous modes of the inductors cycles and control of the current seen across the load. For example in continuous mode if you can find out what duty cycle you need to step down 12v to 3v. In that particular case you need a 25% duty cycle in our theoretical ideal circuit.

This is due to D (uty cycle) =Vout/Vin =0.25 duty cycle.

http://en.wikipedia.org/wiki/Buck_converter

b) Boost converters-

Note: the switch is typically a MOSFET,IGBT, or BJT.

Idea: voltage regulation by the inductor--

Also energy stored in an inductor is described as-

The circuit above is used to take a DC voltage and raise it to a higher DC voltage. The DC-to-DC power converter uses switched-mode power supply (SMPS) containing at least two semiconductor switches (a diode and a transistor) with at least one energy storage element, a capacitor, inductor or the two in combination. Filters made of capacitors(sometimes in combination with inductors) are normally added to the output of the converter to reduce output voltage ripple.

This is also called a "step up converter" because it steps up the voltage source. Since power must be conserved (P=VI), the output current is lower than the source current. And as mentioned in the Buck converter, we use the inductors capability to control the voltage, due to the rate of change of current across itself. Boost converters are often used for DC sources such as batteries, solar panels, rectifiers and DC generators.

The circuit analysis is quite similar to the buck converter. As mentioned in that section, we use the inductor to resist changes in current, thus controlling the voltage. In a boost converter, the output voltage is always higher than the input voltage.

The basic principle of the boost converter consists of two distinct states as see above:

1) The on state: the switch is closed, resulting in an increase of inductor current

2) The off state: the switch is open and the only path offered to the inductor current is through the flyback diode, the capacitor C and the load R. This results in transferring energy accumulated during the on state into the capacitor connected in parallel with the load.

To find out what duty cycle you need to say convert 12v to 24v then use the duty cycle conversion equation. D = 1-(12/24) = 1-0.5 = 0.5.

c) PWM-

Used for controlling power to inertial electrical devices, made practical my modern power switches. Longer the switch is on compared to off periods, the higher the power supplied to load is. PWM is use for several electronic application, including: telecommunications signal modulation, power delivery to a load, voltage regulation, and audio effects/amplification. An example of how PWM is used to convert digital signal to an analog signal is shown below.

Above is an example to control speed of a motor. Lets say the duty cycle = time on/time off = 0.5 voltage swings from 0 to 12 volts. Then average voltage = 0.5 * 12v = 6volt average being supplied to the motor.

**Also used for Digital to Analog converter.

From my experience , an easy way of creating a duty cycle could be done by using a microcontroller which you can turn off and on an output voltage that is controlled with a timing interrupt. A wonderful reference for a PWM driver can be found on my professor Valvano's website (http://users.ece.utexas.edu/~valvano/EE345L/Lectures/LLec27_PWMmotor.pdf)

Example code of a timer to create PWM on an ARM processor can be found below.

Here are some examples of duty cycles:

// Timer0APWM.c

// Runs on LM3S811

// Use Timer0A in PWM mode to generate a square wave of a given

// period with 50% duty cycle.

// Daniel Valvano

// June 27, 2011

/* This example accompanies the book

"Embedded Systems: Real Time Interfacing to the Arm Cortex M3",

You may use, edit, run or distribute this file

as long as the above copyright notice remains

THIS SOFTWARE IS PROVIDED "AS IS". NO WARRANTIES, WHETHER EXPRESS, IMPLIED

OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF

MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.

VALVANO SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL,

OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.

For more information about my classes, my research, and my books, see

http://users.ece.utexas.edu/~valvano/

#define TIMER0_CFG_R (*((volatile unsigned long *)0x40030000))

#define TIMER0_TAMR_R (*((volatile unsigned long *)0x40030004))

#define TIMER0_CTL_R (*((volatile unsigned long *)0x4003000C))

#define TIMER0_TAILR_R (*((volatile unsigned long *)0x40030028))

#define TIMER0_TAMATCHR_R (*((volatile unsigned long *)0x40030030))

#define TIMER_CFG_16_BIT 0x00000004 // 16-bit timer configuration,

// function is controlled by bits

// 1:0 of GPTMTAMR and GPTMTBMR

#define TIMER_TAMR_TAAMS 0x00000008 // GPTM TimerA Alternate Mode

// Select

#define TIMER_TAMR_TAMR_PERIOD 0x00000002 // Periodic Timer mode

#define TIMER_CTL_TAEN 0x00000001 // GPTM TimerA Enable

#define TIMER_TAILR_TAILRL_M 0x0000FFFF // GPTM TimerA Interval Load

// Register Low

#define TIMER_TBILR_TBILRL_M 0x0000FFFF // GPTM TimerB Interval Load

// Register

#define GPIO_PORTD_AFSEL_R (*((volatile unsigned long *)0x40007420))

#define GPIO_PORTD_DEN_R (*((volatile unsigned long *)0x4000751C))

#define SYSCTL_RCGC1_R (*((volatile unsigned long *)0x400FE104))

#define SYSCTL_RCGC2_R (*((volatile unsigned long *)0x400FE108))

#define SYSCTL_RCGC1_TIMER0 0x00010000 // timer 0 Clock Gating Control

#define SYSCTL_RCGC2_GPIOD 0x00000008 // port D Clock Gating Control

void WaitForInterrupt(void); // low power mode

// period is number of clock cycles in PWM period ((1/clock) units)

void PWOut_Init1(unsigned short period){

volatile unsigned long delay;

SYSCTL_RCGC1_R |= SYSCTL_RCGC1_TIMER0;// activate timer0

SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOD; // activate port D

delay = SYSCTL_RCGC2_R; // allow time to finish activating

GPIO_PORTD_DEN_R |= 0x10; // enable digital I/O on PD4

GPIO_PORTD_AFSEL_R |= 0x10; // enable alt funct on PD4

TIMER0_CTL_R &= ~TIMER_CTL_TAEN; // disable timer0A during setup

TIMER0_CFG_R = TIMER_CFG_16_BIT; // configure for 16-bit timer mode

// configure for alternate (PWM) mode

TIMER0_TAMR_R = (TIMER_TAMR_TAAMS|TIMER_TAMR_TAMR_PERIOD);

TIMER0_TAILR_R = period-1; // timer start value

// TIMER0_TAMATCHR_R = period/4; // duty cycle = 75%

TIMER0_TAMATCHR_R = period/2; // duty cycle = 50%

// TIMER0_TAMATCHR_R = 3*period/4; // duty cycle = 25%

TIMER0_CTL_R |= TIMER_CTL_TAEN; // enable timer0A 16-b, PWM, 50% duty

}

//debug code

int main(void){

// PWOut_Init1(300); // initialize timer0A in PWM mode (20,000 Hz)

// PWOut_Init1(1200); // initialize timer0A in PWM mode (5,000 Hz)

PWOut_Init1(6000); // initialize timer0A in PWM mode (1,000 Hz)

while(1){

WaitForInterrupt();

}

d) LDO-

http://www.analog.com/library/analogDialogue/archives/41-05/ldo.html

For the circuit above (LDO) the output voltage is defined as

A "low-dropout" regulator is used for DC voltage regulators which operate with a very small input-output differential voltage. The advantage for using a low dropout voltage is because they a lower minimum operation voltage, but higher efficiency operation and heat dissipation.

Primarily, the main components for an LDO circuit consists of a power FET and a differential amplifier (error amplifier). One input of the differential amplifier monitors the fraction of the output determined by the resistor ratio of R1 and R2. The second input to the differential amplifier is from a stable voltage reference (bandgap reference). If the output voltage rises too high relative to the reference voltage, the drive to the power FET changes to maintain a constant output voltage.

These LDO regulators work in the same way as all linear voltage regulators, however the main difference is their schematic topology. Instead of an emitter follower topology (shown below, low-dropout regulators use open collector or open drain topology. This allows transistor saturation, which allows the voltage drop from the unregulated voltage to the regulated voltage to be as low as the saturation voltage across the transistor.

Figure: PNP version of the emitter follower circuit

Just for my reference, I added a quick discussion of transistors. The transistor allows it to function as an amplifier or switch. This is accomplished by using a small amount of electricity to control a gate on which larger supply of electricity. The transistor's supply of voltage is comparable to turning a valve to control a supply of water.

Transistors have 3 parts: base, collector, and emitter. The base is the gate controller for the device for larger electrical supply the emitter is the outlet for the supply. The collector is the larger electrical supply, and the emitter is the outlet for that supply. By sending varying levels of current from the base, the amount of current flowing through the gate from the collector can be regulated. In this way, a very small amount of current may be used to control a large amount of current, for example within an amplifier. The same process is used to create binary code for digital processors, but in this case a voltage threshold of 5 volts is needed to open the collector gate. This process allows the transistor to be used as a switch with binary function of - 5 volts = on and less than 5 volts = off.

e) Advantages of FIR vs IIR filters

A wealth of information on FIR filters can be found here: http://www.eas.uccs.edu/wickert/ece2610/lecture_notes/ece2610_chap5.pdf

A wealth of information on IIR filters can be found here:

http://www.eas.uccs.edu/wickert/ece2610/lecture_notes/ece2610_chap8.pdf

Quick notes about the above information:

x[n] is the input signal,
y[n] is the output signal,
are the filter coefficients, also known as tap weights, that make up the impulse response,
is the filter order; an th-order filter has (N+1) terms on the right-hand side. The x[n-i] in these terms are commonly referred to as taps, based on the structure of a tapped delay line that in many implementations or block diagrams provides the delayed inputs to the multiplication operations. One may speak of a 5th order/6-tap filter, for instance

FIR- current input depends on pas and previous input samples as well as previous output samples.

	IIR (feedback)- y[n] = b0x[n]+b1x[n-1]+...+bmx[n-m] - a1y[n-1]-a2y[n-2]-any[n-N]	FIR- y[n] = b0x[n]+b1x[n-1]+...+bmx[n-N] = sum from i= 0 to N (bi * x[n-i])
stability	Can be unstable, can have limit cycles	Liner phase always possible, no limit cycles
Order	less	more
History	Derived from analog filters	No analog history
other		Polyphase implementation possible can always be made causal.
	Use less memory and calculations than similar FIR filters	More memory
	Recursive implementations (short order)	Too long and may cause various application problems (long order)

IIR filters are difficult to control and have no particular phase, where as FIR filters make linear phase always possible. IRR can be unstable, whereas FIR is always stable. IIR, when compared to FIR, can have limited cycles, but FIR has no limited cycles. IIR is derived from analog, where as FIR has no analog history. IIR can make polyphase implementation possible, whereas FIR can be made casual (linear time-invariant system; depends only on past and present inputs, not future).

Rolodecks and Medic Strategies for Pl_goldrush ...

2011-03-13T03:40:00.000-05:00

1) snipers
Rolodecks : About the snipers.
Rolodecks : Know who he is and check the scoreboard often.
Rolodecks : You HAVE to communicate when he's down.
Rolodecks : That's the time-frame when it's absolutely safe for you to roam around.
Rolodecks : Whoever takes him down.
Rolodecks : I constantly check that shit.
Rolodecks : It's highlander, not 6v6 where there's a potential class change.
Rolodecks : So just match the name up with the class.
Rolodecks : Not that hard to do, but keep up on it.
Rolodecks : If he gets...
Player Ms. Awesome joined team Spectator
Player Ms. Awesome joined team RED
Rolodecks : Just join red and walk around with me.
Rolodecks changed team name to D: :<
Rolodecks : But, anyway, stay on top of the sniper.
Rolodecks : Because...
Rolodecks : The only way you'll keep him in check is with your own sniper/spy.
Rolodecks : Which is important because like I said...
Rolodecks : You're his number one target.
Rolodecks : If they're good no amount of dodging/cover will save you.
Rolodecks : Well cover saves you but it's map specific.
Rolodecks : And there are "holes" so to speak.
Rolodecks : I tend to jump around alot, strafe unpredictably.
Rolodecks : CROUCH
Rolodecks : Because this throws them offf.
Rolodecks : Certain guys hit moving targets well but can't hit a still target for shit.
Rolodecks : Um..
Rolodecks : Yeah just communicate about their sniper, it's key
Rolodecks : Unless he's shit which in that case still worry about it.
Rolodecks : Whoever takes him out..
Rolodecks : Let the team know it.
Rolodecks : They can't fake death like spies anyway, so it's surefire.
Rolodecks : If they don't have a mic then have them tell you some other way.
Rolodecks : Or just watch the kills in the upper right.
Rolodecks : Or check the scoreboard.
Rolodecks : You all have a mic?
Rolodecks : Oh, good!
Rolodecks : That solves that then.
Rolodecks : Um...
Rolodecks : If the sniper's up...
Rolodecks : Kinda look around to see who he's shooting at.
Rolodecks : If you wanna chime in at any time feel free to.
Rolodecks : I"m just ramblin' on.

2) healing orders/when to heal

Rolodecks : Yeah this map ain't too health friendly.
Rolodecks : They should be leaving them for you.
Rolodecks : Uh...
Rolodecks : Well that's not always good, consider respawn times.
Rolodecks : Of the packs.
Rolodecks : The smaller ones pop up more frequently.
Rolodecks : Not sure but it's map specific.
Rolodecks : Believe it or not.
Rolodecks : I don't have it memorized, just something I've noticed.
(Voice) Ms. Awesome: MEDIC!
Rolodecks : I think all valve maps are pretty much a straight ilne.
Rolodecks : Uh...
Rolodecks : Everybody's gonna want heals when they're "in the red."
Rolodecks : Just how it is.
Rolodecks : The key to winning...
Rolodecks : Out of the gates or just in general?
Rolodecks : Out of the gates...
Rolodecks : If you have to do a rollout like...
Rolodecks : On push maps like badlands...
Rolodecks : 5cp maps...
Rolodecks : Always..
Rolodecks : ALWAYS
Rolodecks : Soldier, then demo...
Rolodecks : Reason being...
Rolodecks : You'll always heal at the max rate during the initial spawn.
Rolodecks : Meaning...
Rolodecks : Don't let the soldier/demo do their jumps....
Rolodecks : UNtil they're full buffed by you first.
Rolodecks : You can heal before you "move" during the initial start.
Rolodecks : Y'know?
Rolodecks : Before you unfreeze...
Rolodecks : So tag them and have everybody else crouch.
Rolodecks : Well yeah but same concept.
Rolodecks : Scouts are very important to keep buffed.
Rolodecks : In highlander anyway.
Rolodecks : Just gotta know where the sentry is.
Rolodecks : But...
Rolodecks : Keep him buffed as much as possible, he'll thank you.
Rolodecks : He's about in the middle of my general heal order for highlander, depending on his individual skill.
Rolodecks : Alright, I was saying...
Rolodecks : Good heal orders...
Rolodecks : Goes like this...
Rolodecks : Bleed/fire first.
Rolodecks : Always.
Rolodecks : Unless somebody else is at critical/red health.
Rolodecks : And you're not in a warzone situation...
Rolodecks : Reason being, the fire/bleed makes your uber charge faster.
Rolodecks : Makes you heal more health before they get to 150% overheal, which is the sweet spot.
Rolodecks : For uber percentage rates.
Rolodecks : Which is also key.
Rolodecks : You don't wanna like...
Rolodecks : Constantly heal just one or two guys unless you're making a push.
Rolodecks : But I'm sure you know the relationship already.
Rolodecks : It's a trifecta.
Rolodecks : Heal rate/ubercharge rate/overheal.
Rolodecks : Uber charges at anywhere from 40 sec. to 80 sec.
Rolodecks : Kritz is 35-70 I believe.
Rolodecks : No, no...
Rolodecks : You're gonna max out your ubercharge rate if you heal...
Rolodecks : If you heal guys until they hit overheal.
Rolodecks : And you stay on them and just overheal them, that's when it slows down.
Rolodecks : You can, but...
Rolodecks : The rate gets halved.
Rolodecks : You ubercharge the fastest doing raw healing.
Rolodecks : Once they're topped off and you're just maintaining, you're losing the race.
Rolodecks : I mean, it's good to keep 'em overhealed....
Rolodecks : But keep it in mind.
Rolodecks : Would you rather have a kritz in a minute or 35 seconds?
Rolodecks : Word.
Rolodecks : Ubers win games.
Rolodecks : Warpy?
Rolodecks : Yeah he's a god.
Rolodecks : Don't get careless.
Rolodecks : I never was a big fan of running kritz in highlander, to be honest.
Rolodecks : Reason being, you don't have the firepower much.
Rolodecks : I know, but...
Rolodecks : Preference I guess.
Rolodecks : But keep the ubercharge rates in mind.
Rolodecks : You only charge at "fast" or "slow".
Rolodecks : There is a third rate, but that's only when you're healing somebody who's already being healed by a second medic or a DISPENSER
Rolodecks : Which is why I ALWAYS ask them to step away from the dispenser.
Rolodecks : Don't have them do that.
Rolodecks : Ask them to step away.
Rolodecks : Because it turns your rate to shit.
Rolodecks : Yes, you're aware of the conccept then.
Rolodecks : You don't have to worry about a second medic, so we'll skip that.
Rolodecks : Just a refresh.
Rolodecks : :D
Rolodecks : You gotta grind it into your head.
Rolodecks : Anyway, who are you generally rolling with?
Rolodecks : Class-wise?
Rolodecks : Like who do you stay around?
Rolodecks : And heal most of the time?
Rolodecks : Oh, go ahead then.
Ms. Awesome : demo, solly, pyro
Ms. Awesome : since our heavy seems to come and go...
Ms. Awesome : as of late
Rolodecks : Is your soldier jumping alot and getting picks?
Ms. Awesome : yes, tinkelp has been doing pretty well with helping me build
Rolodecks : Oh, good.
Ms. Awesome : and our demo, warpy, also helps me build quite a bit
Rolodecks : That's why I'm a fan of sticking with the soldier.
(Voice) Ms. Awesome: MEDIC!
Rolodecks : Easiest class to build uber with.
Rolodecks : Demo's not feasible.
Rolodecks : Most of the time.
Rolodecks : High self damage.
Rolodecks : Slow reload.
Ms. Awesome : the solly generally sticks with me quite a bit
Rolodecks : Needs to be on the offensive.
Rolodecks : You need to stick with the heavy.
Rolodecks : Well...
Ms. Awesome : and he watches my ass when we are about to make a push
Rolodecks : HE needs to stick with you.
Rolodecks : Because to be honest...
Ms. Awesome : yes, the heavy really does
Rolodecks : He's helpless without a med.
Ms. Awesome : yeah
Rolodecks : And if the enemy heavy's stickin' with their med...
Ms. Awesome : i agree
Rolodecks : Game over if you run into them.
Rolodecks : Because he's easily one of the best classes with a medic up his ass.
Rolodecks : Unstoppable.
Rolodecks : Don't care what they say.
Ms. Awesome : the heavy does help us push quite a bit
Rolodecks : On a map like this...
Ms. Awesome : but again, our heavy has changed so much...
Rolodecks : Well just kinda guide him.
Rolodecks : Ask him to kinda just follow ya around.
Ms. Awesome : ok
Rolodecks : He's obligated to.
Rolodecks : Also, have him pack some form of healing for you.
Rolodecks : No shotgun allowed, that's my rule. :p
Rolodecks : Minigun's so great of a weapon anyway.
Rolodecks : In maps like this you want the high ground.
Ms. Awesome : since working with warpy, he sarted using the fists of steal
Rolodecks : Your soldier's not gonna be sticking with you much I hope.
Rolodecks : He's got the mobility on his side.
Ms. Awesome : yeah
Rolodecks : Just buff him up and let him fly.
Ms. Awesome : he genearlly romes
Rolodecks : He's gonna get picks easily.
Ms. Awesome : *roams
Rolodecks : Demo is necessary to stick with.
Rolodecks : not only for sentry nests...
Rolodecks : But it's warpy, he's a god.
Rolodecks : He needs you like you need him.
Ms. Awesome : true
Rolodecks : Heavy/demo is all I really use 99% of the time.
Rolodecks : Soldier depending on their playstyle.
Rolodecks : Because...
Rolodecks : Scout's gonna be poppin' in and out, heal him whenever he lets you.
Rolodecks : Don't really run to him, it'll get you killed.
Rolodecks : let him come to you for heals.
Rolodecks : Tell him to grab healthpacks in enemy territory.
Rolodecks : It's his job anyway, to flank and get the medic.
Rolodecks : Find the sentry.
Rolodecks : Etc.
Rolodecks : He's kinda pairin' up with the spy to be honest.
Rolodecks : Both need to be sneaky bastards.
Ms. Awesome : who is, the scout?
Rolodecks : So neither are really on your list of concerns.
Rolodecks : Yes.
Rolodecks : He's most effective behind the lines
Ms. Awesome : true
Rolodecks : It's easy for him to do so, being 1 of each class.
Ms. Awesome : i never thought of it that way
Rolodecks : Even if all he's doing is just running in there and getting killed...
Rolodecks : A distraction of sorts...
Rolodecks : It'll focus attention on him.
Rolodecks : Have your spy cloak, and get behind there without a scratch.
Rolodecks : Wreak havoc.
Rolodecks : Diversion.
Rolodecks : Psychological warfare.
Rolodecks : But anyway....
Rolodecks : Get ubers as fast as you can, maintain overheal.
Rolodecks : Also, remember...
Rolodecks : Sometimes I'll have really heavy combat classes stand for about 5/10 seconds then heal them.
Rolodecks : Reason being is that your medigun heals at 3 rates.
Rolodecks : 24/48/72 health/sec.
Rolodecks : Depending on how fresh their wounds are.
Rolodecks : i.e. when they last took damage, seconds ago.
Rolodecks : If they took damage less than 5 seconds you'll heal at 24/sec.
Rolodecks : Which is nice for building uber, but not so good for healing raw health output.
Rolodecks : 5-10 sec (I think?) is 48/sec.
Rolodecks : Middle ground for health/ubercharge rate.
Rolodecks : Until you cap overheal.
Rolodecks : After 10 sec. it's 72/sec.
Rolodecks : Just keep that in mind.
Rolodecks : I'd have guys stand around for a few seconds, it's more efficient really only with the heavy and soldier.
Rolodecks : Since they have the most health and the math adds up.
Rolodecks : Efficiency, but not really practical.
Rolodecks : Since you want that uber.
Rolodecks : But anyway...

3) Who NEEDS to stay with you at all times?
Rolodecks : Stick with heavy/demo mostly.
Ms. Awesome : so about staying alive when using crits (even though you don't like kritz)
Rolodecks : Let the sniper go after their sniper.
Rolodecks : He's the only counter to that.
Rolodecks : Did that help a bit?
Ms. Awesome : definitly
Rolodecks : I'm not done yet. :p

4) Crits/Uber
Ms. Awesome : but what about staying alive when using crits?
Rolodecks : I'd like to show this in action but am unable to do so at the moment, so this is all you'll get from me.
Rolodecks : Nothing much you can do about that.
Rolodecks : The reason being you've got no overheal.
Rolodecks : Since there's no second medic.
Rolodecks : Which is why I never was a fan of kritz much in highlander.
Rolodecks : You're too vulnerable.
Rolodecks : The only way it works is if you catch them off guard.
Rolodecks : Which in maps like granary/badlands it's great.
Rolodecks : Payload, not so much.
Rolodecks : Espeically if you're on defense.
Ms. Awesome : yeah
Rolodecks : Which is the only viable option to use it anyway.
Rolodecks : You need to get that sentry.
Ms. Awesome : so from what i am understanding from most players is...
Rolodecks : If it's in a good spot the only way you'll push through is with an uber.
Ms. Awesome : crits = defense; uber = offense
Rolodecks : Not exactly...
Ms. Awesome : at least for payload/this map
Rolodecks : More like...
Rolodecks : Uber = Safety/passive playstyle.
Rolodecks : Kritz = Aggressive/ambush.
Rolodecks : Kritz is very situational.
Rolodecks : And 90% of the time the uber's gonna be a better option.
Rolodecks : If not just as effective.
Rolodecks : Kritz is great for chokepoints.
Rolodecks : If they're all bunched up, kill 'em before they can retreat.
Ms. Awesome : good point
Rolodecks : Which is why heavy's a bad kritz/uber target in almost every situation.
Rolodecks : Because he's gotta spin up.
Rolodecks : And can't move.
Rolodecks : Kritz soldier can rocket jump while keepin' the beam on him...
Rolodecks : Launch some krit rockets...
Rolodecks : Game over for them.
Ms. Awesome : but when are good times to use crits on this map?
Rolodecks : Same with crit demo, lob pipes/stickies over a hill outside of the line of sight.
Ms. Awesome : that you can think of?
Rolodecks : Up here if your engi gets a foothold...
Rolodecks : Reason being...
Rolodecks : If you can sneak through here...
Rolodecks : It's not feasible, but if you get a kritz back here...
Rolodecks : Sticky here.
Ms. Awesome : game over huh...
Rolodecks : Edge their gun here...
Ms. Awesome : at their spawn
Rolodecks : Sniper's gonna be here most likely.
Ms. Awesome : oh damn
Rolodecks : Boom.
Ms. Awesome : that is leathal
Rolodecks : Problem is...
Rolodecks : It's hard to do.
Rolodecks : Because...
Rolodecks : Look here...
Ms. Awesome : and spawning
Rolodecks : Too easy to see.
Rolodecks : So you gotta be careful.
Ms. Awesome : sniper could spot me pretty easy
Rolodecks : NEVER STAY UNDER HERE.
Rolodecks : EVER.
Rolodecks : Death trap.
Ms. Awesome : i've noticed
Rolodecks : This is literally a shit map for highlander..
Ms. Awesome : death valley
Rolodecks : For two reasons...
Rolodecks : 1. snipers have too much line of sight on this last cap point.
Rolodecks : 2. sentries also have too much line of sight.
Rolodecks : 3. It's hard to push becasue their pyro's gonna push ya back.
Ms. Awesome : yeah
Ms. Awesome : we have been working on that
Rolodecks : 4. Don't really use kritz.
Rolodecks : I mean...
Rolodecks : No matter where their gun is, if the engi's alive...
Rolodecks : And whackin' his buildings...
Rolodecks : You're not gonna out-damage him.
Rolodecks : His repairs, anyway, unless you all team up on him.
Rolodecks : Which is only gonna get you killed.
Rolodecks : Use your ubers for dealing with the sentries.
Rolodecks : Have your team mates push up behind ya and clean house.
Rolodecks : Don't focus fire on sentries, ever.
Ms. Awesome : plus, that peskey wrangler
Rolodecks : That's what they want you to do.
Rolodecks : EXACTLY.
Rolodecks : Kill the engi when you uber sentries.
Rolodecks : Espeically if they're wrangled, they're always close by.
Ms. Awesome : good point
Rolodecks : Shuts down the gun, take it out.
Rolodecks : Get close.
Ms. Awesome : good point
Rolodecks : Always do the demo in this case.
Rolodecks : Soldier if you have no one eles
Ms. Awesome : sniper needs to know his que to get the engi
Rolodecks : Heavy's not good unless you jump from above.
Rolodecks : Sniper should focus on the enemy sniper above all else.
Ms. Awesome : ah
Ms. Awesome : true
Rolodecks : If he can take out the engi, then the engi ain't doin' a good enough job of hiding. :p
Rolodecks : Like I said earlier, sniper's your number one thread.
Ms. Awesome : very true
Rolodecks : Threat.
Rolodecks : Meaning...
Rolodecks : He, along with a lesser extent, the spy, can take you out without you even seeing him.
Rolodecks : Or doing anything about it.
Rolodecks : I always play cautious until I know their sniper's down.
Rolodecks : Or when I know I have some cover to walk around in.
Rolodecks : But this map doesn't have that saving grace.
Rolodecks : Because like I said, wide open areas at both cap points.
Rolodecks : As you know by now.
Ms. Awesome : oh yes
Rolodecks : Not much you can do about that, hope they miss.
Rolodecks : ALWAYS pop if necessary.
Rolodecks : Just intuition, sometimes I've hit it and felt the little "ping" as they've pulled the trigger for a headshot a hair too late
Rolodecks : It works.
Ms. Awesome : so earlier, i was fussed at by some of my team members for poppoing too early
Rolodecks : Wait...
Ms. Awesome : *popping
Rolodecks : What caused you to pop uber?
Rolodecks : And by what class?
Ms. Awesome : i just felt that it was unsafe for me to jump out there with just one person
Ms. Awesome : i knew the entire team was out there
Rolodecks : Don't push like that.
Ms. Awesome : i know
Rolodecks : Stay with at least TWO other people at all times. Sorry, continue.
Ms. Awesome : people were off classing
Ms. Awesome : in a lobby
Ms. Awesome : so yeah, i was quick to hit that uber
Rolodecks : What caused you to pop?
Rolodecks : And which class made you do it?
Ms. Awesome : heavy
Ms. Awesome : demo
Ms. Awesome : but yes, i realise i popped to early
Rolodecks : Don't ever let their demo start bombin' stuff your way.
Rolodecks : You're fucked 99% of the time.
Rolodecks : Blast radius.
Ms. Awesome : but the team work was not there (in the earlier match)
Rolodecks : Understandable.
Rolodecks : What health were you at when you normally popped?
Ms. Awesome : full
Ms. Awesome : oh normal
Rolodecks : ???
Ms. Awesome : umm
Ms. Awesome : generally under 50
Rolodecks : Alright, general rule of thumb...
Ms. Awesome : when i decide to pop and there are many players surrounding me
Rolodecks : 105 or under, and feeling doubt, pop it.
Rolodecks : Over 105, keep it.
Rolodecks : Until you take another hit.
Rolodecks : Because that's the general damage cap for rockets and demo nades.
Rolodecks : So unless you get headshot or backstabbed...
Rolodecks : That 105 health gives you some time to react.
Rolodecks : If you pay attention.
Rolodecks : Because..
Rolodecks : You'll never see that dive-bombing soldier behind you...
Rolodecks : Who fires a rocket at your ass and drops your uber...
Rolodecks : If you're at 50 or so health and just hanging on to it.
Rolodecks : Don't be that person.
Ms. Awesome : soldiers do not really bug me too much
Rolodecks : 105 is the magic number here.
Rolodecks : Yeah but some will.
Rolodecks : The good ones are gods at killin' medics.
Rolodecks : I've had it happen to me, heh.
Rolodecks : 105, 105...
Rolodecks : Magic number.
Rolodecks : When in doubt, pop.
Rolodecks : Because a shit uber is still better than none at all.
Ms. Awesome : so yeah
Rolodecks : I don't recomment kritz on this map at all.
Rolodecks : I mean if you absolutely HAVE to use it...
Rolodecks : Use it on defene.
Ms. Awesome : tomorrow, i think i need to play it safe
Rolodecks : Defense.
Rolodecks : But even then...
Rolodecks : Abuse the chokepoints, like where you're standing.
Rolodecks : A single crit rocket, fired about here...
Rolodecks : Or here...
Rolodecks : Splash is lethal.
Rolodecks : Other than that, if they're medic's smart he's not gonna be on that cart when it's going around that bend.
Rolodecks : Snipers watch that.
Ms. Awesome : note, i generally crit the demo because of his tremendous experience
Rolodecks : Kritz medics love that spot.
Rolodecks : they're gonna be up here...
Rolodecks : Ubering outside of this.
Rolodecks : Out the window, hit the underpasss.
Rolodecks : The only good time to be here.
Rolodecks : With a demo, hole up here.
Rolodecks : Don't uber unless you have to, on offense.
Rolodecks : Cut up here...
Rolodecks : Uber here if you want.
Ms. Awesome : yeah i've been sniped by snipers up in the left window
Rolodecks : There?
Ms. Awesome : yes
(Voice) Ms. Awesome: MEDIC!
Rolodecks : Have your spy get up there.
Ms. Awesome : good idea
Rolodecks : Spy/scout are the best at calling shit out.
Rolodecks : Sniper to an extent too.
Rolodecks : But he's got tunnel vision.
Rolodecks : once you know...
Rolodecks : Their sniper/sentry spot...
Rolodecks : If you have an uber you can most likely win with a little teamwork.
Rolodecks : If you uber that way with the demo, here...
Rolodecks : Good idea to have..
Rolodecks : Another class come through here...
Ms. Awesome : so, when holding good choke points use crits on this map
Ms. Awesome : otherwise, uber is better
Rolodecks : Well kritz is risky because...
Ms. Awesome : continue
Rolodecks : It's only really good when the cart's right here.
Rolodecks : This map is far too wide open.
Rolodecks : For kritz to do much damage.
Rolodecks : At the key areas.
Ms. Awesome : right, but warpy can really spread out damage
Rolodecks : I know, but if they're really bunched up they're a stupid team. :p
Ms. Awesome : unlike a solly
Rolodecks : I mean there's gonna be guys around the med...
Rolodecks : But other than that it's in vain.
Rolodecks : Do what you want
Ms. Awesome : ok
Rolodecks : But a demo like warpy is just as good with an uber.
Ms. Awesome : i'll have to remind him of this... :P
Rolodecks : But then again I focus heavily on sentry gun destruction.
Rolodecks : Mostly, on blue.
Rolodecks : On maps like this.
Rolodecks : Because there's nothing you can really do about a sentry here.
Rolodecks : Even a soldier here...
Rolodecks : Can't outdamage the repairs.
Rolodecks : Yeah they like to put nests up here.
Rolodecks : It's easy to take out there though.
Rolodecks : Very easy.
Rolodecks : You can edge the stairs.
Rolodecks : Well...
Rolodecks : Like I said, have your heavy stick with you.
Rolodecks : Always.
Rolodecks : Well, don't let him slow you down if you know what I mean.
Rolodecks : He's a horrible uber target most of the time...
Ms. Awesome : yeah
Rolodecks : But probably the best bodyguard.
Ms. Awesome : good point
Rolodecks : Demos are the shit with ubers.
Rolodecks : But are shit at defending you.
Rolodecks : Unless they can aim their nades.
Rolodecks : Because stickies don't fire fast enough.
Rolodecks : Also self damage.
Rolodecks : Soldier's middle ground but I liked to have ours on our last team go for flanks/dive bombs/sneaks/medic picks.
Rolodecks : Kind of a spy lite version.
Rolodecks : But that's up to you, I'm sure my team is a lot different from yours.
Ms. Awesome : ours is special
Rolodecks : If you're gonna use kritz then use it at the choke points.
Ms. Awesome : lol
Rolodecks : But don't use it all the time.
Ms. Awesome : but yeah
Rolodecks : Switch if you have to.
Ms. Awesome : oh and what about that vita saw
Rolodecks : But uber is extremely effective, if not necessary, on both sides of this map.
Rolodecks : I never was a fan.
Rolodecks : Like I said, if you do the math..
Rolodecks : 40-80 sec. range on the uber.
Rolodecks : 35-70 on the kritz.'
Rolodecks : It's not saving you much.
Ms. Awesome : true
Rolodecks : Ubersaw does more for you in ONE SWING.
Rolodecks : And you'll still have your ten extra health.
Rolodecks : Which comes in handy.
Rolodecks : I've wrote the damn thing off, honestly.
Rolodecks : The buff it got...
Rolodecks : About seeing enemies' health...
Rolodecks : Is that in the beta only?
Rolodecks : Still?
Ms. Awesome : yeah
Rolodecks : Well either way...
Rolodecks : It's pretty much useless.
Rolodecks : Because with damage indicators on...
Rolodecks : You see the damage your pocket does.
Ms. Awesome : i actually haven't see anything about seeing the enemy's health
Rolodecks : You can just add it up.
Ms. Awesome : *seen
Rolodecks : And kinda tell if they're in the red.
Ms. Awesome : k
Rolodecks : I honestly don't use it, ever.
Rolodecks : I know some top medics that do but I call 'em craz.
Ms. Awesome : i get it.. i get it...
Rolodecks : Ubersaw's just too good.
Ms. Awesome : yep
Rolodecks : Use the amputator as an alternative, but I never was a fan of standing in one spot.
Ms. Awesome : same here
Ms. Awesome : i never use it
Rolodecks : it's all about uber advantage.
Rolodecks : And using them wisely.
Rolodecks : Do you...
Rolodecks : Aside from that...
Rolodecks : It's all team specific, really..
Rolodecks : Unorthodox strategies work.
Rolodecks : If you practice.
Rolodecks : I have a vid I wanna show you.
Rolodecks : Later.
Rolodecks : About a minute long.
Rolodecks : Oh.
Rolodecks : Well I hope this helped.
Rolodecks : What uh...
Rolodecks : What's the map after this?
Rolodecks : D:
Rolodecks : You disappoint me.
Rolodecks : Anyway...
Rolodecks : I hope this helped, it's hard for me without a mic...
Rolodecks : But that's just general overview
Rolodecks : Uh...
Rolodecks : Stick with 2 people.
Rolodecks : Heavy and whoever else at the time.
Rolodecks : Mainly.
Rolodecks : 105 is the magic number.
Rolodecks : Uber rates.
Rolodecks : Overheal's important.
Rolodecks : Just prioritize.
Rolodecks : If you have 5 guys shouting for heals.
Rolodecks : Tell them to calm the fuck down.
Rolodecks : And wait their god damn turn. :p
Rolodecks : Because you can't fight physics.
Rolodecks : I hope this helped, I feel like I'm just telling you shit you already know.
Rolodecks : Just trust your team mates
Rolodecks : Use them as meat shields.
Rolodecks : Crouch.
Rolodecks : Zig zag.
Rolodecks : Always watch your back.
Rolodecks : I turn a 180 at least every 5 seconds in-game.
Rolodecks : It's very rare for a spy to kill me.
Rolodecks : Anyway...
Rolodecks : Copy the chat log if you want.
Ms. Awesome : thank you
Rolodecks : But just keep those points in mind.
Rolodecks : I'm sure you'll do fine, talk to the team about what we discussed.
Ms. Awesome : i think you covered everything i needed to understand
Rolodecks : I'm sure you'll pull something out of this.
Ms. Awesome : oh i will
Rolodecks : :D
Ms. Awesome : :)
Ms. Awesome : again, thank you
Rolodecks : Glad to be of service.
Rolodecks : I mean, strategy gets a lot deepr.
Rolodecks : Like I'm not sure if you know how to cheat the healbeam. :p
Ms. Awesome : i am willing to learn
Rolodecks : But that's for another time.
Rolodecks : Deep shit
Rolodecks : Oh.
Ms. Awesome : umm.. i wouldn't mind hearing about that
Rolodecks : Please, don't use the crossbow.
Rolodecks : At least in highlander
Rolodecks : Piece of shit weapon.
Ms. Awesome : lol
Ms. Awesome : i hate that weapon
Rolodecks : It's really up to you if you use blut/syringe gun.'
Ms. Awesome : i never use it
Rolodecks : Both are pretty much equal in my eyes
Rolodecks : I like blut alot in highlander though.
Rolodecks : To be honest.
Rolodecks : The extra heal rate...
Rolodecks : Is good when there's alot of bleed/afterburn...
Rolodecks : But...
Rolodecks : You've got healthpacks.
Rolodecks : And a heavy with hopefully a sandvich.
Rolodecks : Which is very necessary.
Rolodecks : No shotguns allowed!
Rolodecks : Uh...
Rolodecks : Anything else you need?
Ms. Awesome : nope
Ms. Awesome : i think that's it
Rolodecks : OH
Rolodecks : Bind a key to your "Ubercharge ready!" command.
Rolodecks : I have mine bound to "r".
Rolodecks : Fake 'em out.
Rolodecks : Don't overdo it though.
Ms. Awesome : except for good places to keep hidden on this map
Rolodecks : OH'
Rolodecks : They're kinda obvious.
Rolodecks : Anywhere their sniper can't get y a.
Rolodecks : You talkin' red or blue?
Rolodecks : I like the rocks here.
Rolodecks : The phallic, penis shaped rocks are your friend.
Rolodecks : As you see here.
Rolodecks : Reason being...
Rolodecks : Here...
Rolodecks : They can drop down, true.
Rolodecks : But you'll always see it.
Rolodecks : You've got...
Rolodecks : A nice pocket here.
Rolodecks : Here too.
Rolodecks : use the cliffs.
Rolodecks : NEVER stay in the house.
Rolodecks : Too cramped.
Rolodecks : Splash/sniper kills ya.
Rolodecks : It's hard, so just try to keep a minimal line of sight.
Rolodecks : If their sniper's down and I'm feeling aggressive...
Rolodecks : Then I'll usually hook up here.
Rolodecks : And uber
Rolodecks : To buy some time.
Rolodecks : Only do that if you know you can get their med.
Rolodecks : Otherwise you lose uber advantage.
Rolodecks : Just know the status of their medic/sniper at all times.
Rolodecks : And kinda have a rough idea of his ubercharge percent.
Rolodecks : And just beat him to the punch.
Rolodecks : Don't overextend thoug.
Rolodecks : You're on defense, kinda let them come to you;
Rolodecks : I mean, once they hit a certain part of the map lock it down with your sentry and other sorts...
Rolodecks : But there's no need to play offense on defense.
Rolodecks : If ya catch my drift
Ms. Awesome : yep
Rolodecks : It does your team no good if you, the medic, are behind the enemy team if you're red
Rolodecks : If you're blue it's a different story, like I showed you.
Rolodecks : But defensive flanks are no where near as effective.
Rolodecks : Mainly because blue has the upper hand on spawn times.
Rolodecks : And they spawn so much closer to the action.
Rolodecks : So it's kind of a waste.
Rolodecks : It all boils down to team chemistry.
Rolodecks : And communication.
Rolodecks : Come up with shit on the fly, try it out..
Rolodecks : If it don't work then find something else.
Rolodecks : Other than that that's about it.
Rolodecks : Cover is your friend.
Rolodecks : Rocks are good on defense.
Rolodecks : But try and keep the high ground.
Rolodecks : It's easier to kill guys who are below you
Rolodecks : Especially with your projectiles like nades/rockets/etc.
Rolodecks : So try and have your soldier keep the high ground.
Ms. Awesome : alright
Ms. Awesome : well, its been nice chatting with you
Ms. Awesome : i think these tips are going to help tomorrow
Rolodecks : WHOA
Ms. Awesome : ?
Rolodecks : Shit TF2 freezin' on my ass.
Rolodecks : Well I hope this helps you guys.
Ms. Awesome : i hope it does too
Rolodecks : I gotta get some rest, big day tomorrow!
Rolodecks : D:
Rolodecks : Talk it over, do you need a copy of the chat log?
Ms. Awesome : whats going on tomorrow for you?
Ms. Awesome : oh sure
Rolodecks : Nothing except sitting on my ass
Ms. Awesome : lol
Rolodecks : Wishing I could walk up and down these things we call "stairs".
Rolodecks : :p
Ms. Awesome : would you like to specate our match tomorrow?
Rolodecks : Depends on the time.
Ms. Awesome : 9pm cst
Rolodecks : Central time?
Ms. Awesome : yes
Rolodecks : So 8pm my time...
Rolodecks : Gotcha.
Rolodecks : Oh, one more thing...
Rolodecks : Watch this.
Rolodecks : Back up a bit.
Rolodecks : Little more.
Rolodecks : Alright come forward a bit.
Rolodecks : Just until my beam breaks.
Rolodecks : Alright.
Rolodecks : Stay there.
Ms. Awesome : ok
Rolodecks : Notice I can't lock on to you anymore.
Rolodecks : With my medigun.
Rolodecks : Even though I was just healing you at that range.
Rolodecks : That's cheating the beam.
Rolodecks : You're always gonna have a longer range when you keep your beam on them...
Rolodecks : Then after it breaks.
Rolodecks : This is why rocket jumping soldiers are so good when you keep your beam on them.
Ms. Awesome : nice
Rolodecks : It's not a very big distance, no...
Rolodecks : But most guys don't know about this.
Rolodecks : Abuse it with kritz.
Rolodecks : It makes a difference, trust me.
Ms. Awesome : so what do you do after it breaks?
Rolodecks : You gotta get closer to them, of course.
Ms. Awesome : lol
Ms. Awesome : yes
Rolodecks : See?
Rolodecks : But, yeah, just a neat little trick.
Ms. Awesome : oh do you use any special config files?
Rolodecks : That you can add to your gameplay.
Rolodecks : Haha, my config is all my own tweaking.
Rolodecks : I don't have access to my cfg files though.
Rolodecks : They're on my computer, this is my brother's...
(Voice) Rolodecks: Thanks!
Rolodecks : I use a custom hud.
Ms. Awesome : oh right
Rolodecks : The Community Hud, with some medic tweaks...
Rolodecks : And...
Rolodecks : A custom autoexec file too.
Rolodecks : Among numerous other things.
Ms. Awesome : i have one to help ping
Rolodecks : Hmm...
Ms. Awesome : in autoexec
Rolodecks : What's the file look like?
Rolodecks : Is it a buncha cl_ stuff?
Rolodecks : interp and such?
Ms. Awesome : cl_cmdrate "67"cl_interp "0.016" // Change to 0.024 for hitscancl_interp_ratio "1"cl_lagcompensation "1"cl_pred_optimize
Rolodecks : Hmm...
Rolodecks : Well the cmdrate's fine...
Ms. Awesome : warpy gave me the commands
Rolodecks : But everything else you'll have to change depending on your raw ping to the server itself.
Rolodecks : Because...
Rolodecks : It's all ping specific in the end.
Rolodecks : cl_forcepreload 1 should be in there.
Rolodecks : Somewhere.
Ms. Awesome : no, actually it is not
Rolodecks : cl_updaterate 66
Ms. Awesome : that must be in the config file
Rolodecks : It's probably not.
Ms. Awesome : this is autoconfig
Rolodecks : All your autoexec file does is just input those commands in the console when your game boots up...
Ms. Awesome : right
Rolodecks : It's not in your settings nor the steam cloud....
Rolodecks : Needleguns fire ten syringes a second.
Rolodecks : Uh...
Rolodecks : Never get in the habit of huffing your kritz for health.
Rolodecks : Unless you're gonna die from afterburn/bleed.
Ms. Awesome : oh and how do you bind your mele wepon to mouse 3 again?
Rolodecks : Uh...
Rolodecks : I don't know I just use my mousewheel...
Rolodecks : I do have my viewmodels turned off though.
Rolodecks : So I don't see them, I go by sound/indicators.
Ms. Awesome : oh
Ms. Awesome : i cannot do that
Rolodecks : I don't know the specific command for scripting like that...
Ms. Awesome : i need to see things
Rolodecks : I use a custom crosshair too.
Rolodecks : So it never changes either.
Ms. Awesome : same here
Rolodecks : Like how different weapons have crosshairs different.
Rolodecks : So it's really key for me to hear stuff and stay on it.
Rolodecks : But in the long run I've found it's worth it.
Rolodecks : But different strokes for different folks.
(Voice) Rolodecks: Help!
Rolodecks : So...
Rolodecks : I'm sure En Ex could help you on that one.
Ms. Awesome : oh yeah
Rolodecks : Because I'm about as useful as tits on a boar hog.
Ms. Awesome : haha
Rolodecks : With this stuff, honestly.
Ms. Awesome : why?
Rolodecks : Because I've never bothered with scripting.
Rolodecks : Or keybinds or shit like htat.
Rolodecks : Except for my fake uber call.
Ms. Awesome : yep
Rolodecks : I suggest you do the same.
Ms. Awesome : so when do you use that call?
Rolodecks : I mean it's on your voice menu...
Rolodecks : x + 8.
Rolodecks : Uh...
Rolodecks : Just whenever.
Rolodecks : Like I really only use it when...
Rolodecks : I can get them to bluff theirs.
Rolodecks : But even then..
Rolodecks : You'll wanna bind a second key to...
Rolodecks : Your...
Rolodecks : Third voice menu...
Rolodecks : The C one.
Rolodecks : C + 6.
Rolodecks : And use it for when you DO get an uber you won't shout out like this..
Rolodecks : Because that's loud.
Rolodecks : And gives you away.
Rolodecks : c + 6 is the most quiet voice commands for medic.
Rolodecks : So that's what I hit as soon as I get 100%, so it overwrites the "I am fully charged!" voice command.
Rolodecks : So it's more quiet.
Rolodecks : More sneaky.
Rolodecks : So fake it once with your fake call.
Rolodecks : But when you actually hit uber hit that other key.
Rolodecks : So they can't hear it as well.
Rolodecks : And they'll never know when you actually have a charge or not.
Ms. Awesome : oh nice
Ms. Awesome : lol
Rolodecks : So, yeah...
Rolodecks : Hope that helps.
Ms. Awesome : so instead of uber charge ready... you hit c+6
Rolodecks : The less knowledge you give them, the better.
Rolodecks : Yes, because you'll always call out when you hit 100% y'know?
Rolodecks : So you just hit that key instead.
Rolodecks : Of just doing nothing.
Ms. Awesome : ok
Rolodecks : So you'll stop that original line from triggering.
Ms. Awesome : sweet
Rolodecks : And instead it'll sound like this...
Rolodecks : A little less obvious.
Ms. Awesome : yeah i wouldn't know what that meant
Rolodecks : You don't understand?
Ms. Awesome : plus, i communicate when i have the uber/crits
Ms. Awesome : so everyone would know
Rolodecks : I'm talking about the other team, they'll hear you.
Rolodecks : They hear that voice line.
Ms. Awesome : true
Rolodecks : Instant give away.
Rolodecks : here's a demonstration, watch my ubercharge.
Rolodecks : percent.
Ms. Awesome : lol
Rolodecks : Now if you didn't know...
Rolodecks : You'd never know I had an uber.
Rolodecks : Unless you looked at my gun.
Rolodecks : Because the barrel glows...
Rolodecks : When you have a charge, it's easy to tell.
Ms. Awesome : how did you change that? just a bind?
Rolodecks : Just the same thing you do for the fake call out.
Rolodecks : Aww you missed it. :D
Rolodecks : Now I know you're charged.
Ms. Awesome : haha
Ms. Awesome : well, i can't change it now
Rolodecks : Just ask en ex about binding voice commands.
Rolodecks : Or somebody, not much help here...
Rolodecks : Sorry!
(Voice) Ms. Awesome: Yes
Rolodecks : But those two are key.
Ms. Awesome : i can figure it out
Rolodecks : Everything else, fuck it.
Ms. Awesome : haha
Ms. Awesome : that's my #1 strat
Rolodecks : You'll do well.
Rolodecks : Pretty sure I'll be able to spectate.
Rolodecks : If I do I'll watch you.
Ms. Awesome : cool
Rolodecks : I won't ghost or nothin'.
Rolodecks : But there's gonna be a delay on the source tv anyway.
Rolodecks : if they're smart.
Ms. Awesome : source tv
Ms. Awesome : yeah
Ms. Awesome : send me a message if i don't send you one
Rolodecks : Pretty sure I'll remember.
Rolodecks : It's on a sticky note on my monitor onw.
Ms. Awesome : wow
Ms. Awesome : i feel special
Ms. Awesome : haha
Rolodecks : Well my brother's monitor.
Ms. Awesome : anyways, thanks again
Ms. Awesome : maybe someday i'll be giving the tips...
Ms. Awesome : lol
(Voice) Rolodecks: MEDIC!
(Voice) Rolodecks: MEDIC!
Ms. Awesome : uh how did you do that?
Rolodecks : Timing.
Ms. Awesome : haha
Ms. Awesome : well, i have no timing
Rolodecks : You'll get it.
Rolodecks : There's a reason it's banned...
Rolodecks : Allows you to move while you're kill taunting.
Rolodecks : YOU GOT IT
Rolodecks : Can't do it on stairs.
Rolodecks : Ledges/drops only.
Rolodecks : Anyway...
Rolodecks : Gonna hop on main for a bit.
Ms. Awesome : kk
Rolodecks has found: The Sandman
Rolodecks has found: The Ullapool Caber
Ms. Awesome : oh was there a link you wanted me to see?
(Voice) Rolodecks: Help!
Rolodecks : Oh, right.
Rolodecks : Watch this for inspiration really quick.

Team Fortress Competitive Medic Tips from Pure

2011-02-27T06:27:00.000-06:00

Medic strategies from pure---- (http://forums.steampowered.com/forums/showthread.php?t=1735510&page=7)

1) Pocketing:

A)Soldier only?
Pocketing a soldier A LOT is a thing of the past. You can view
Pandemic-Reptile demos and you will see the exact way to do that.

The new style and most effective style, is having a more aggressive
pocket. This means that he isn't always just jumping in, but he chooses
the right time to completely leave his medic, to use his ability and 300
health to cause havoc.

The best time for a pocket soldier to do this is when he knows his
roaming soldier just respawned and is 3-4 seconds away, and he decides
it is worth his life to go RocketJump in.

2) Kritz or uber?:

Kritz, good ole Kritzzzkreig.

At the high level the legitimacy of Kritzkreig tends to come and go.

People get better at defending against it and teams come up with more
creative ways to use kritz.

Rule: Never use kritz on defense, unless you're back is against the wall
and you think the faster build rate will help.

Try to use kritz when you are attacking a teams last. Aim to get 2-3
kills with the kritz. Does not always have to be the medic. Often
killing 3 people is better then dropping the med.

Gravelpit = Use the kritz a lot on demos. Aiming at spire, aiming at the
back of B house from long, etc

Push maps = Kritz to surprise at middle or pushing on teams lasts. Kritz
soldiers in tight areas.

In general though it is best to just use Uber and master an aggressive
uber, a defensive uber, a multi-uber, and FAT* ubers.

When I was on complexity and we were destroying everyone, we ran kritz
in scrims just to make the games interesting. I used a tactic called
grinding the kritz. whenever I got it, I would basicaly just hit it, so
no one knew when to attack us, they just kept randomly dieing to kritz.

*FAT uber means you are only keeping it one person and they get a very
nice and long UBER.

3) Healing orders

A) General tips--
The best way to get better at Medic is actively practice healing
orders.

What is it like to give the pocket soldier A LOT of heals....

What is it like to give the scouts A LOT of heals....

Depending on your team and your teams strengths you should heal
accordingly.

Identify on your team who is the best and explain to your team, " I am
going to be healing (this scout) and (this soldier) A LOT this game."

See how it works out, and then try the opposite the next game.

B) Mid-fight healing orders--

Quote: Pure, tell me how my team can win midfights on badlands because
we're VERY inconsistent! What can I do as a medic other than having the
best heal order I can on the rollout, and surviving to get outside and
heal the demo+everyone else?

Answer:
You need to watch your STV demo from a 3rd
person point of view. View the mid fight from a birds eye view:

See who is attacking together

Who is attacking alone

Who is running from the fight

Who is missing their shots

See if you are healing the right person

See if you just got out dm'd

See if you just got out strat'd

There is no one way to play badlands mid, and its constantly evolving.
Why don't you come up with a new strat and set the scene on its heels?

C) Healing Scouts--

Question:
How dependent should the roamer and scouts be on getting heals or buffs
from the medic? I feel like it kills momentum and leads to the pocket's
death sometimes, but I could be wrong.

Answer:
Yes it is up to the medic to deny the roamer/scouts, and it is up to the
medic to communicate that they are pushing. Often as roamer i just want
a quick tap, not a heal. Im 80, I want 130. I am 160, I want 200. I try
not to stop the momentum. "DONT HEAL ME" The medic needs to make the
decision on who to heal. Let people die if you want, its your show. Well
the pocket, uhm, generally you want the pocket alive all the time, but
that is a symbiotic relationship. The pocket must realize the situation
his team is in and make the best push or hold decision.

4) Medic self defense

Question:
Do you have any tips on self defense as Medic? I'm already pretty good
at stutterstepping thanks to playing Scout as well and faired decently
when being attacked by a Scout, but I got divebombed by the roaming
Soldier quite a few times. How do I escape those? And when on my own,
should I try to go for the saw hit or SPAM needles?

Answer:
Well generally you need to start identifying when a roaming soldier is
coming. Either very early in the fight, when your team takes a lot of
damage, or when you have yet to see him and are in a commited position.
Try to position yourself to surf the rocket. Practice the timing of
jumping and crouching. The big trick to rocket surfing... besides
watching a 10 minute tutorial on how to do it... thank you
blackymonster... is to take the rocket on your side, don't be afraid to
take the damage, the damage is propelling you. Defending yourself is
also highly dependent on the skill level of player you are dealing with.
Certain escapes against HIGH level players just do not work against low
level players.

I have played turbine with European teams, and complexity. We destroyed
EG and Nexus on Turbine. I am always very aggressive in the initial mid,
giving my life to get my players in the key positions to max buff. The
next trick is to sit on the upper left stairs, and use the high ground
to you advantage. If you honestly want to win, you just need to wait,
wait, wait, wait for them to push out and then you counter uber. Yes on
turbine one of the biggest skills is knowing when to go to your base or
to go to mid. When in doubt everyone meet in your base and "stop the
bleeding." Do not let 2 caps, turn into 5 caps.

5) When to leave your team

Quote: See, I play with guys that aren't exactly the brightest crayons
in the box, you know? And so they often run in and then I get killed
along with them. Should I run away when something like this happens to
save my uber? I feel a little guilty just abandoning them to their fate
like that.

Also, regarding loadouts, I heard you mention that you like using the
Syringe/Blut with the Ubercannon and Ubersaw. When do you use the
Kritzkrieg?

And finally, when a team mate goes down, or when they're at a point
where healing is no longer effective (they're missing a lot of shots and
aren't really able to kill the person that's fighting them, but the
person fighting them isn't aiming too well either), should I pull out my
gun and try to assist in killing instead of healing them and waiting for
them to kill them? And when should I use my ubersaw? Very good question
about when to leave your people.

Answer:
If your uber is above 70 you should almost always run. It is much better
to meet up with your team again and have uber immediately than to be
agggresive when you almost have uber.

Secondly, you need to learn the range of your pocket soldier's
intelligence. You said you have some dumbos on your team. Well, you
should message them in private before the game and say: Please make an
effort to realize when it is just me and you and we need to escape. I
need you.

He should listen, if he does not, I would get a new pocket.

Depending on the style and aggresion of your team you should create your
own little ruleset on when to leave your team to live another day.

I follow a pretty straight forward ruleset. I focus on the initial picks
of the push. Who goes down, who gets rolled, etc. If our team gets two
picks at the beginning of the push, we know we can push and do it up
big. If we LOSE two members prior to the push, we know immediately that
our flank is in trouble and eventually we will have people on us.
Backup? Sure, but why not take one person into the whole team and uber,
making them multi uber and freak out?

Pay attention to who dies at the start of the push. Do a +/- quickly in
your head. Keep your players health all above 100% percent as best you
can. But most importantly develop a relationship with your pocket. Or
break up :")

When to aid in your teammate?
You should aid him when the enemy he is attacking is totally oblivious
to you or is it out of ammo. When they are out of ammo, peoples heart
rates pick up, and their aim starts to suffer. So why not get a free
ubersaw. Do not be limited in your Medic play, test the craziness, test
the conservative style, and see what works best.

6) Dodging spam:

Medic Tip: On cp_badlands when you round the corner approaching your
enemy's spire, stay in that area and practice dodging spam.

Stay in harms way on purpose and see how long you can dodge spam and
maintain good heals.

In a match you are going to want to enter the choke, navigate around
spam, staying in relation to your pocket, and try to over heal the
classes that go up to spire. Scouts, demo, and roamer.

After you have reached a safe point, and you dont feel the need to rush
in with uber, walk up the spire as a medic. It is much safer and allows
you to bypass 3-4 chokes where you can spammed.

7) Spies:

Quote: Anyways I was wondering about when a spy is ever run in 6 v 6 (I
know he's not used a lot, but are there certain situations in which a
spy would be better than a scout?), or do people just do it for fun?

Ans:
The spy has made its return to the scene with gunboats soldier being so
viable. This means that since the game is becoming even more aggressive
and less calculating that its sometimes much easier for spies to
navigate. Traditionally you would just have two stagnant soldiers
standing around, and two scouts not +forwarding. It is the opposite now.
The only classes around the medic are demo/pocket, so it is much easier
for a Spy to use an aggressive distraction to back stab 1-2 of the combo
on a repeated basis.

8) Scouts:

Question:
I'm having A LOT of trouble dealing with a scout when my nearby
teammates have died. What's your advice? Just keep running hoping your
team's scouts or recently respawned demo/roamer saves you? Backpaddel
while 'supressing' him with needles? Or fight him head on as the
situation is pretty much lost anyway, hoping to take him down with you?

Answer:
When it comes to escaping from scouts you need realize if you can book
it and make it, you need to immediately start fighting, or you can run
and suppress.

I always immediately just turn and book it. If the scout is far enough
away he will never catch you if you book it.

9) Medic targeting

Quote: In real situations, the medic is usually a much harder target
than his patient, usually because you can't actually see the medic,
while the patient is shooting your face.

One of the more important skills to learn is target selection. Always
going after the highest value target is not always the best solution,
because if the medic is any good, he's going to position himself to make
that difficult and costly.

Winning a point without a medic because the other team sacrificed too
many players for the medic pick happens all the time.

---

For sensitivity, just pick one and stick with it. There is no magic
number that will improve your aim, but constantly fiddling with it or
setting it super high or low because "that's what the proz do" will
certainly mess it up.

Ans:
Nail on the head. Choosing a target is tough
stuff. I am a roaming soldier now, and one of the main practice is
gunboat suiciding and target selection. I will jump 50 times in a game
and constantly practice which targets I should aim at in different
situations.

Zargon is right again when it comes to not overemphasizing the medic.
The whole reason some medics are hyper aggressive is that they enjoy
other teams going after them. Id rather keep healing everyone on my team
in the middle of the fight, dodging for the life of me, and dieing....
than sitting in the back doing absolutely nothing.

When it comes to sensitivity I would recommend staying near one
sensitivity but there is no problem occasionally moving it up and down.
Do not constantly do it, but, for instance, if you think you are not
hitting your flick rockets well enough, you can up your sens and it
might be easier.

10) Medic Loadout

Medic loadout: Syringe Gun, UberCharge, Ubersaw

When I am feeling fancy I will use Blautsauger. Ubercharge is standard. Ubersaw saves matches.

http://www.youtube.com/watch?v=ab0J0Uqhmcc

11) Medic Communication:

A) Question:
I find it hard to direct my team and give them orders (scouts stick
together, roamer move in now, demo sticky up left side etc) while also
coordinating my pocket etc (scout flanking! Inc soldier jumping! etc)
AND dodge like a maniac. Should I expect my teammates to do stuff like
sticking up certain places and sticking together? or not?

Answer:
Really good questions guys, I appreciate it. The more effort you put in,
the more effort I put in.

You should not have to direct your whole entire team. To a certain
extent you are observing your team, like a commander at the rear of the
army, and therefore you should make Macro calls.

By having to focus on so many different variables you will eventually
slip up yourself. I will give you a real example.

When I first joined compLexity, the team was a machine. Enigma/Carnage
unstoppable, SolidSnake amazing, and very good soldiers. It was easy for
me to come in and just give them the sick heals and they would do sick
things.

After two seasons, SolidSnake stopped caring as much, and our scout
combo was slowly being caught up to. It got to a point where I would
have to micro way too much. So much to the point that it stressed me out
and made me not enjoy the game.

There is a limitation to what you should be saying and what calls you
should be making. My best piece of advice is to start small. Meaning,
say the things that need to be said not EVERYTHING. Whenever I have a
medic who is literally saying everything, I say: Would you please stop
commentating the either game.

It is important to have clear sounds so you can stay focused.

Good things to say:

Heals are at "house/back left/right side/on hill" You are my pocket It
is just us, fall back Our flank just died Medic
tagged/?????/weak/stacked You are all weak, relax Healing scout then
roamer then pocket

x) General Defense (concerning entire team)

Quote: So a rather general question about pushing. How should a team
practice pushing onto a defense? If you look at Invite level TF2,
Intermediate TF2, low-level competition, and public play, you will find
many attack styles that generally all miss the mark.

It is important to think about your attack from the defender's point of
view. Like, what would you NOT want an offense to do to you?! In general
you must do that.

First lets identify what the defense has setup:

Medic with Uber

Soldier with 300 health

Sticky Trap

Sniper

Roaming Soldier covering flank

Engineer with Sentry

Now, what do you have on offense:

Medic with Uber

Soldier with 200-300 Health

Roamer ready to spam sentry or engage the demo

Scouts ready to spring free once the sentry is down

Demo able to take down a sentry and sticky the point

The table is set.

PRACTICE

You need to practice three types of things.

1) killing the medic or forcing the uber with an isolated attack

2) killing the demo or forcing him to blow his trap with an isolated
attack

3) taking down the sentry prior to going in by double spamming with
soldiers/demo

A few things that are important to know:

Your scouts are useless unless the sentry is down'

Your demo needs to sticky the point

Your roamer and/or scouts need to work the point by either suiciding on
it or jumping on and off. This will bring the enemy tot he point and
your demo will kill 1-4

The quality of your push is dependent on how clean you get into the area
and when you uber your soldier and demo. You want to make sure they are
ubered when they are max health, so when they leave you post uber, they
have a high chance of being affective.

Get back to me once you've practiced this stuff.

x) Map Tips:

A) Yukon

B) Granary
Quote: Originally Posted by breloom Do you have any advice on how to get
out of open?

Also adrenalynn, I'm not pyyyour, but in my as a soldier on granary,
it's really best not to jump the crates to try to control them, but to
just jump on the other team's heads at the same time. When the scouts
get to mid they should call out the scouts of the other team and sort of
check them, which is the best way to keep your medic alive, because if
you dedicate a soldier to babysitting your medic, the other team's
soldier ends up on your medic's head and your medic is respawning.
Basically, don't try to ward off attackers or hold crates, instead bring
the fight to them.

Answer:
Breloom hit the nail on the head. Soldier jumps on
Mid granary continue to evolve on a daily basis. Meaning the weak are
getting eaten alive and the strong survive.

I am literally playing a Granary match tonight where I am the roaming
soldier. So I guess I will just tell you exactly what I do.

Depending on where my medic spawns, depending on how fast my demo is to
mid, and depending on if we get an initial kill or death, I will do an
assortment of aggresive jumps.

Like Breloom said, just jumping on your box, and spamming and sitting is
relatively worthless. I do actually jump up there a lot but I move
quickly to my next target.

Assuming we go left to mid, and I equalize, here are 4 things I do as
roamer:

1) RJ to mid left and go onto point and spam whats on point and then RJ
at demo/medic

2) RJ to back left and spam their garage and then RJ at
scouts/demo/medic

3) Double RJ off crate into medic and kill him

4) RJ on crate, identify where combo is, jump in combos direction.

That is literally what I am going to be doing tonight.

Mid granary is an elusive situation. You can be destroying middle for
weeks and then the whole game switches up and your style is left in the
dust.

Practice being hyper aggressive, and really passive, see which pays off.

The 4 things i mentioned are mainly used to take pressure off of me team
and to put a kill strike at the more important targets. And since I use
gunboats I can escape post-kills almost all the time.

C) Freight

Question:
Any tips on Turbine and Freight? On Turbine the huge amount of SPAM
pretty much forced me into using Kritz because I hardly got the time to
get a full Uber, and the opposing Medic fell into that same strategy
after us. Positioning between offense and defending the Flag was very
troubling as well. My issues with Freight mainly lie in pushing last,
where the (when looking from last) left entrance gets you SPAMmed, the
mid entrance gets you Sniped, and the right entrance gets you SPAMmed
AND Sniped.

Answer:
Freight? God I loathe middle. Even when you middle it does not even feel
like you won anything of consequence.

When attacking last on freight you need to show multiple fronts and
activiely change where you are healing from in order to keep the sticky
traps guessing and sniper not very comfy.

Identify where the sentry gun is, see if you can jump your demo roamer
in.

Make sure to put pressure on the sniper. You should be able to uber in
with your demo and take out the sentry gun and force the uber.

That should be your continuous attack, ubering in with demo to take down
gun and medic, and hoping you win the post-uber fight.

D) Granary

Do you have any tips for pushing last on Granary when both teams have
uber and the defending team has a heavy? Sorry I have been planning
Valentines Day and have been relatively busy with my team. I have
already explained how to attack a heavy. It is in one of the previous
comments. Additionally though, the heavy requires a lot of resource, so
if you focus the other targets, the medic sometimes makes a mental error
and just lets everyone his team die by sticking on his heavy. But
please, read the first comment.

Learning Linux and programming C

2011-02-15T11:51:00.000-06:00

After installing the virtualbox ubuntu machine on my Window 7 machine, I had some problems getting used to doing some basic commands (since I have been a Windows user my entire life). I have compiled a list of common commands I use.

Ps. I highly recommended adding the guest addons to increase the screen resolution for the Linux virtualbox. It looks lovely. To do this follow these steps...

How to Install Guest Additions on Ubuntu 10.10?

Additional packages and updates released by ubuntu people to test with VB. You can download them and install by following method to get high screen resolutions. This worked in one host and not in other for me. So, I’m not 100% sure this will work for all. Please share your results on comments area.

Make sure virtual machine is having internet with download access. Open terminal ( Application –> Accessories –> Terminal)

Type

sudo apt-get update

and provide the root password, above command will check and download the updates available on internet server.

Type,

sudo apt-get install build-essential linux-headers-$(uname -r)

Now, type,

sudo apt-get install virtualbox-ose-guest-x11

Restart and check the screen size, seamless and full screen mode on ubuntu 10.10, all should work.

Let me know how it worked for you.

Your screen will come out to a pretty resolution like follows.

----

My current list of common linux commands

cd: changes directory. Example) cd desktop

ls: shows contents of current folder

gvim: opens up graphical vim editor

chmod 777 <name of program to change permissions>: to change permissions when it states "./<nameofprogram> permission denied"

gcc -ansi assembler.c -o <programoutput>: to compile a file with gcc ansi-c compiler produces an executable file a.out (default) or <programoutput>

a.out <inputfile> <outputfilename>: If your program does not have any errors, you will notice that the above command produces an executable file
named a.out. This is the standard name for the executable created by gcc unless you provide your own preferred name.

./a.out <inputfile> <outputfilename>: If the above doesn't run your program try running it by typing this.

gcc -ansi -o assemble assembler.c: If you would like to call your executable with a different name, you need to use the -o option of gcc.
For example, if you want your executable named assemble, you need to compile the source code for your assembler (assembler.c) with the following command.

gcc -lm -ansi -o assemble assembler.c: If you decide to use any of the math functions in math.h, you also have to link the math library by using the command.

./assemble <inputfile> <outputfilename>: To run your assembler now, just use the following command.

man gcc: If you would like to learn more about gcc, try the following on the UNIX command prompt.

Video Laser Art

2011-02-03T10:35:00.001-06:00

Something I wouldn't mind tinkering on in the future (http://www.muonics.net/blog/index.php?postid=15). My friend Cassy is working on a similar project like this. This looks pretty fun...

GRL Laser Tag Rotterdam - how to and source code

February 20, 2007

UPDATE: !!!!! LASER TAG 2002 IS RELEASED - Feb 2008 !!!!!

The main event of the GRL Rotterdam tour - 'L.A.S.E.R TAG' - 60mw geek graffiti madness.
Watch the video here on the Graffiti Research Lab website.

In the spirt of GRL's and Eyebeam's open source beliefs, we are posting the code and executable
for the Laser Tag application online for you to download, dissect, reuse and hopefully improve. The code is
C++ and compiled in a super old school Codewarrior IDE for windows but it is oepnGL based and written
using openFrameworks which is a cross platform library for writing creative code. So it should be very
straight forward to run in Visual Studio, DevC++ or even xcode on a mac.

In its simplest form the Laser Tag system is a camera and laptop setup, tracking a green laser point across
the face of a building and generating graphics based on the laser's position which then get projected back
onto the building with a high power projector.

There are a bunch of things you need to do to get Laser Tag up and running yourself, so here follows the required
equipment and setup instructions. This will assume that you using windows but it will also apply for other OSs too.

EQUIPMENT

We used:

1 PC Laptop - ASUS A8JS - Core 2 Duo 1.83 Ghz 1GB Ram Nvideo Geforce Go 7300 256MB - VGA and DVI out.
1 Pansonic PTD5600U 5000 ANSI Lumens 1024x768 DLP Projector.
1 Watec 221S Security/Astrononmy Camera with manual iris zoom lens.
1 Bogen magic arm and super clamp.
1 Pinnacle PCTV USB capture card.
1 60mW Green Laser (super illegal in a lot of places and very dangerous)
and loads and loads of AAA batteries.

SETUP

Location:

Choose a building or wall that the laser shows up well on. If using a building make sure the lights aren't on
as this will make the tracking of the laser beam harder (also it is not a good idea to point powerful lasers
at a building with people in it) .

Pick a spot far enough back that the projector can overshoot the building by a couple of feet on all sides.

Alignment and calibration:

If the building is vertically orientated and the projector can handle it, put the projector on its side so you are
using the full image of the projection.

Fix the projector in place and then fix the camera underneath the lens of the projector so that it is looking at the
projection area. Allow the camera to see a little more than the projection area so that you can designate an area
as a clear button.

Make sure all the settings on the camera are set to manual - no auto exposure or gain control etc. Adjust the color
balance of the camera so that it looks as natural as possible - make sure any lights in the shot don't look green as this
will confuse the tracking sytem.

Software setup:

Set your resolution of your screen to 1024 by 768.

Connect the projector to the PC and in your display control panel set the display mode to horizontal span.
This should span the Desktop across the laptop screen and the projector so that you have one large screen
of 2048 by 768 resolution. If you have access to openGL and 3D preferences in the control panel, set all settings
to performance.

Connect the camera to the usb capture card and the capture card to the PC. You can use Amcap
to make sure you can capture video okay.

Start the app and you should see something like the image bellow.
Follow the instructions in the diagram to align the camera to the projection surface.

Once the camera is aligned to the projector hide the white alignment lines on the projected image by pressing L.
Turn down the iris of the camera to the point where the surface is as dark as possible but the laser still shows up strong.

Settings:

The settings for the app are saved in an xml file so once you have made your adjustments hit the S key to save your changes.
The up and down arrows on your keyboard will run through the list of settings and the left and right arrows can adjust the values.

The first settings you will want to adjust is the four at the bottom - which define the color tracking of the laser.

Hue Point - should be the value of green that the camera sees the laser as.
Hue Thresh - is how wide a range from the hue point it should consider.
Sat Thresh - is the minimum amount of saturation.
Value Thresh - is the minimum brightness.

Anything that is outside the range of these settings will show up as black in the Thresh Video anything that is whithin
(hopefully only the laser point) should show up white.

Here is an explanation of the rest of the settings:

Slide - slides the screen over so you can see what is being projected
Verticle mode - if the projector is being used on its side.
Use blobs - should stay on, blob tracking ended up being more reliable than motion difference.
Motion diff - don't touch
Use camera - toggle between using the live camera and an included test video.
Drips mode - when on, small drips of paint will descend from the letter forms.
Fade out - slowely fades the image over time - alternative to clear button.
Slant brush - toggles chisel brush and fatcap mode
Clear zone - Use an area of the image as a clear zone, if the laser is detected there it clears the image.

Brush width - Size of brush
Drips freq - How many drips you want - lower is more
Activity thresh - This determines the time before starting a new line, the background screen should flash red whenever a new line begins.
Min blob size - the smaller this value the more sensitive to noise it will be but also the smoother the line motion.
Jump dist - the max distance to draw a line between two captured points, any distance greater means it starts a new line.
Line resolution - how many points to interpolated a line with, higher number means smoother line but uses more cpu.
Clear X - adjust x position of clear area.
Clear Y - same for y
Clear thresh - lower means a more sensitive clear area , higher less sensitive - adjust so that only laser point clears image.

NOTES

Once everything is setup be very careful not to bump either projector or camera as even a move of a 1mm will be
enough to mess the alignment.

The settings are saved in settings.xml file - if you want to back up your settings for a location just zip the file and rename it.

If you are pushed for framerate - try overclocking your graphics with hacked drivers from laptopvideo2go,
you will notice quite a difference!

Press h to hide all gui except the projected image, this can also give you a bump in the framerate too.

DOWNLOAD
UPDATE: !!!!! LASER TAG 2002 IS RELEASED - Feb 2008 - Download Here !!!!!

How to compile C code using gcc on windows (Reference from Amber Jain's Blog)

2011-01-27T22:50:00.002-06:00

In my computer architecture class we need to learn to compile things on Linux. However, I was interested in trying to compile my C code (using a gcc compiler) on a windows machine. Here is what Amber had to say about it (link: http://thinkminus.wordpress.com/2010/05/18/compile-c-code-that-uses-libraries-using-gcc-on-windows/).

Ok. I know that you probably know how to compile code using gcc. You use something like following command:

gcc -Wall -g input_filename.c -o output_filename

gcc -Wall -c -g input_filename.c
gcc -Wall -o output_filename input_filename.c

Right? Ok. RTFM for more details.

The above compile command is really easy and works on Linux, BSD, Unix, Windows etc. On Linux/BSD/Unix, compiling code that uses some library is not so difficult and (almost?) same across different distributions (Makefiles exist to ease the compile/build process). But on Windows, it’s a bit different. Personally, it took me more than half an hour and help of fine folks at #mingw (at irc.freenode.net) to understand how to compile a C program that uses some library.

In this post, I’ll take libcurl as an example to illustrate compiling a C program that uses some library. libcurl is the multiprotocol file transfer library.
For this post, we will try compiling and building (an executable) using following example code:

Source: http://curl.haxx.se/libcurl/c/simple.html


#include <stdio.h>
#include <curl/curl.h>


int main(void)
{
// Source: http://curl.haxx.se/libcurl/c/simple.html
CURL *curl;
CURLcode res;
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
res = curl_easy_perform(curl);
/* always cleanup */
curl_easy_cleanup(curl);
}
return 0;
}

NOTE: Download and extract this to C:\ so that your directory structure should look like:
C:\libcurl-7.19.3-win32-ssl-msvc\lib\Release
More libcurl downloads are here.

Let me start with the command that is the ultimate purpose of this post (i.e. to compile C code on Windows that uses some library). Here:

gcc main.o -o test_binary -LC:\libcurl-7.19.3-win32-ssl-msvc\lib\Release -lcurllib

Here are details of various command line arguments (in order) in above command:

#1. gcc: The first command line argument, ‘gcc’, is the name of compiler.

#2. main.o: The second argument, ‘main.o’, is the name of object file input to compiler that was previously compiled from source code using:
gcc -Wall -c -g main.c

#3. -o: The third argument, ‘-o’, specifies that the argument immediately following this argument is the name of output binary executable, as per the needs of the programmer (or the person who is compiling the code). Also, see #4 that follows.

#4. test_binary: The fourth argument, ‘test_binary’, is the name of output binary executable, as per the needs of the programmer (or the person who is compiling the code). This is bind to ‘-o’ command line argument and should immediately follow it. Also, see #3 that precedes.

#5. -LC:\libcurl-7.19.3-win32-ssl-msvc\lib\Release: Now comes the real part (Pause here and remind yourself the actual purpose of this post). The fifth argument, ‘-L’, specifies that the string appended to -L flag/option is the directory that should be searched for library files specified by ‘-l’ flag (Also, see #6 that follows). Mind you, there is *no* space between the option flag (-L) and the library directory name.

#6. -lcurllib: The sixth argument, ‘-l’, tells linker that the string appended to -l option flag is the library that is to be searched for unresolved symbols when linking. The actual file will be something like either libmylib.aor mylib.lib or something similar (@experts: right?).

I must confess here that I’m still unable to use makefiles *on windows* to automate the process of compiling and building (though I tried only for less than 1 hour). Manual compiling is surely cumbersome, but who cares I very rarely compile my code on Windows and so, I’ll get past this hurdle too sometime in future when I get some free time. And, maybe I’ll do a blogpost on it too.

That’s it. I guess that you get it. If you still have questions/problems, you can try following:
1. Get help from #mingw (irc.freenode.net).
2. RTFM. http://gcc.gnu.org/onlinedocs/
3. Stanford’s Unix Programming Tools contains some useful information (It’s really useful, even if it is for Unix. Read it.).

PS: In case you get ‘XYZ.dll not found’ error when running the executable, just find the right DLL(s) [on the internet] that are missing and put them in same directory that contains the binary executable. Easy, isn’t it?

My classes for spring 2011 (last semester as an Undergraduate ECE student)

2011-01-21T17:59:00.002-06:00

This is my final schedule as an undergraduate at UT. I am personally extremely excited about this semester. I absolutely love all the professors that are teaching my classes this semester! They actually know how to teach and keep me interested. They will be hard classes, but I expect to learn alot. Why couldn't every single professor each semester be like this group? I am even psyched about probability!?!?!?

Plus, I get to learn fencing! Yay! Super-classy, huh?

Yesterday, I bought these items form www.blue-gauntlet.com ! I can't wait for them to come in. Fencing is an amazing sport.

http://www.blue-gauntlet.com/store/products/259

http://www.blue-gauntlet.com/store/products/291

TF2 Map Making: What Makes a Good Map?

2010-12-26T21:20:00.000-06:00

Recently, I have been investigating how to create a good map in Team Fortress 2 (TF2) . I found a few good tutorials on You Tube -

How to build a TF2 map Part 1: http://www.youtube.com/watch?v=wO9lNXcE3Tw&feature=related
PHA4T3's How to Make Maps for TF2 Tutorials (Playlist): http://www.youtube.com/watch?v=wQeqVSrAsf0&playnext=1&list=PL05E839C5D915EEBD&index=4

Below you can find some hints that Ubercharge.net talks about how to create a good map here (http://www.ubercharged.net/2008/11/14/tf2-design-theory-what-makes-a-good-map/).

TF2 Design Theory: What makes a good map?

by himmelstoss on November 14th 2008

Not all maps are created equal. Even among the high-quality Valve maps, there are winners, like Dustbowl, and there are absolute failures, like 2fort.

Something sets the best maps apart from the mundane, and it isn’t the blessing of the Almighty Train God, either.

It’s teamwork. Teamwork is undoubtedly the most important aspect of good maps. Let me repeat: it’s all about encouraging teamwork.

A map that encourages teamwork ensures that all (or most) classes can contribute wholly to the team’s offense or defense. This is the biggest shortcoming of symmetrical CTF and CP maps. If a team has to simultaneously worry about attacking and defending, the team splits: the engineers hole up in their bases building impenetrable sentry nests while the rest of the team blindly rushes the other side. Rather than focusing its entire manpower on pushing forward, the team needs to leave a few people behind to defend against the threat of a single scout or spy far behind their lines. The very idea of the game being called Team Fortress 2 fails.

Let me qualify – there are excellent symmetrical maps out there, and there are terrible attack/defend maps, too. I’m only drawing attention to the fact that symmetrical maps require a team to split offensive and defensive responsibilities – as a result, an entire team cannot be involved in an offensive push, even if the team is winning.

Assault maps, however, avoid that problem entirely by ensuring that all players on a team are focused solely on either offense or defense. The remainder of this post will focus on assault map theory, but most of what I’m writing can be applied to symmetrical maps as well.

Teamwork in assault maps

The best fun maps tend to emphasize teamwork. Generally, this means creating a challenge formidable enough that an entire team must work together to win. This helps discourage deathmatch players – solo players rarely stand a chance against an entire team.

CASE STUDY: Gravelpit B

Let’s admit that Gravelpit doesn’t have the greatest rapport with players, and the statistics show that it isn’t even being played the way it was intended. Most defensive teams abandon point A, focusing on an strong defense at point B. It may just be because of this attitude that Gravelpit has a 55% win rate for BLU. Who knows.

Nevertheless, Gravelpit is one of the most perfectly designed maps I’ve ever played. It’s probably the only fun official map that represents each class perfectly; it’s also very well balanced.

Capture point B can be attacked from between 2 and 3 sides: the attackers can attack from behind using the C route and through the two main routes from the spawn. It’s more or less open – making it good for snipers, soldiers, and scouts; but it has only small healthpacks (pyros and medics thus carry a lot of weight here). There are enough dark and/or out of the way places for spies to (de)cloak and disguise, especially under the ramp at the C connecting tunnel. Heavies are very effective here, because there are enough short-to-medium-range firefights that occur here. Finally, the roof is accessible to only scouts, soldiers and demomen; however, the lack of health packs up there make them rather vulnerable. The windows of the building allow demomen to make a good effort to destroy the inevitable sentries inside.

Thus, every single class is well represented here. Moving on to teamwork – offensive pushes here need support. Standing out in the open areas of this zone is signing a death sentence unless one is well-supported by the rest of the team (snipers will have their dots trained on you, sentries will be targeting you, and let’s not forget the pyros that will inevitably show up to ruin your sentry-clearance operation).

B is protected against solocaps by a very long control point timing. In addition, the long control point timing means that the players inside the building capturing the point need to be able to stage a quick defense (hold the point) against a RED onslaught. When inside the building, attack can come from anywhere – even from above! Capturing Gravelpit B is a difficult ordeal, requiring almost complete control of the entire B zone. Clearly, only a determined team effort (or a terrible defense by a RED team that, admittedly, does not have much teamwork) can allow BLU to win this capture point.

Alternate routes

Of course, encouraging teamwork isn’t everything; in addition, teamwork is also a very intangible quality. As a result, let’s move to a more concrete level. Another common feature between all of the best maps: the presence of alternate routes.This theoretically should decrease frustration for both teams. It also allows scouts and spies to be much more effective, by giving them different routes to sneak behind enemy lines with. Finally, it allows a team the element of surprise: attacking through unexpected and undefended routes can be crippling to a poor defense.

No one is safe

To prevent the defense from entrenching themselves too deeply, it is essential that the defense is vulnerable at all times. This goes without saying, obviously, but unless someone is in the spawn, they should never be safe – if they are at a place inaccessible to the other team / other classes, but where they can still attack the enemy, there should be no cover. Essentially, the layout of a map must keep everyone wary of their surroundings.

CASE STUDY: Goldrush, Final Stage

OK, I admit it. Goldrush has nothing on Gravelpit in terms of game balance and equal class representation – RED wins this map almost 80% of the time, after all. At the same time, it’s one ridiculously fun map. I’ve almost certainly spent more time on Goldrush than any other map.

Goldrush, despite its shortcomings, is great for teamwork, because that’s essentially the only way for BLU to win. Based on my experience, it takes more than a heroic team effort from BLU to win the notoriously lopsided first stage.

RANDOM: Ribozyme – now that’s a nerdy, yet classy name. Bio nerds like me rejoice.

But, anyway, let’s skip over to the final capture point. Firstly, the green circle denotes an alternate route. Sadly, hardly anyone actually ends up using this route offensively, despite the fact that a strong offensive push there can absolutely destroy defense. Nevertheless – it provides a fantastic way for spies to slip past the inevitable rocket/grenade/bullet spam clogging the main cart route. Also, it provides a great place for offensive engineers to build forward bases. Trust me on this one, it’s a killer tactic for the last stage – setting up a strong offensive base in that area and maintaining it will increase the BLU team’s chances of winning tenfold.

Having no direct connection to the ground, BLU would definitely find it hard to get up to the sniper deck, and the narrow path into the last zone gives BLU snipers a very narrow view of the deck. However, snipers are far from invulnerable here. The discrete pile of rubble (circled in red) allows spies to sneak up to the sniper deck and wreak havoc. (I once got accused of hacking because I dominated an engineer who repeatedly tried to build up there).

Aesthetics!

There is a reason why this map…

(I’m very sorry to bash your map here, whoever made this, but it admittedly isn’t too great).

…doesn’t hold a candle to this map (cp_boulder_v3 by mapper MrMof).

Aesthetics are a very important part of TF2. After all, most of the charm of the game comes from the cartoony characters and landscapes. It just happens that maps that don’t look good or fit the style of TF2 just aren’t as fun to play. I’m not too fond of some of the community maps, being a total attack/defend junkie myself. However, all of the popular community maps use the TF2 style and use it well. CP_Boulder uses it very skillfully, which is just one of the reasons I’m so fond of the map. CP_Steel also stays in the TF2 style, despite its very unique gameplay mechanics.

Conclusion

The game isn’t called Solo Fortress, is it? Teamwork is an integral part of TF2, and probably the most important aspect of any map. Alternate routes to an objective help keep a map moving and facilitate teamwork by allowing all classes to participate – as opposed to bottlenecks, where only combat classes can be of use. Finally, aesthetics play a very important role in the fun factor of a map. Generally, maps that look good are far more immersive than badly styled maps.

Of course, these are by no means the only things that give substance to a map. It’s up to you to find out what makes TF2 tick and keep that in mind next time you’re in Hammer.

With that said, I really encourage you to try out cp_boulder when you can. It’s on our rotation at theubercharged.net TF2 server.

Adventures in the Land of Python!

2010-12-26T01:54:00.002-06:00

I recently was invited to work on a pro-bono project (created by a Chemist Professor @ Rice) with several colleges from UT Business School & Computer Science, called Cure for the Needy. I am assisting in developing a Python/Django website for chemist's all over the world; hence, providing the users a method to collaborate on molecule synthesis creation. The website's purpose is to generate new and cheaper solutions so that pharmaceuticals can produce needed drugs for diseases. Project website is found here: http://www.cureforneedy.org/.

This is a great learning opportunity for me because I have very little to no knowledge in either of these two languages (Python & Django). I have recently been considering going into the game development field upon graduation from UT. Here I hope to get some experience in the artificial intelligence realm of computing.

Here are some great resources found for Python:

UT CS Python Class: http://www.cs.utexas.edu/users/mitra/csFall2009/cs303/cs303.html
Google code exercises: http://code.google.com/edu/languages/google-python-class/set-up.html
My friend's collection of Python E-books: http://www.andreid.com/storage/python/

Invent with Python
Learning Python (4 edition)
Natural Language Processing
Next-Generation Web Frameworks with Python
Python 2.6 Quick Reference
Python Cheat Sheet

Dive into Python (excellent resource): http://www.diveintopython.org/
Python website: http://www.python.org/doc/

I have experience in several programming languages: C,C++,Java, asymbly, VHDL, HTML ... After a few days with Python, I am quickly coming to the realization that this language is undoubtedly one of the most powerful and easy-to-use languages that I have come across yet.

Open Source Software Helps Computers Use Graphics Chips for General Processing

2010-12-07T12:33:00.000-06:00

Just in case you cannot read the picture above from the IEEE Computer magazine, December 2010.

An Academic research team has developed an open source software tool that lets computers use the processing power of graphics processing units for purposes other than rendering and manipulating images.

North Carolina State University scientists are continuing to work on their optimizing compiler tool, which would let developers write simple application code without needing to know how to program specifically for GPUs.

In essence, the tool takes an application and translates it into another program that does the same thing, more efficiently on a GPU. Computers use GPUs to generate the complex, data-intensive graphics seen in games, virtual reality, data visualization, and other applications, explained North Carolina State associate professor Huiyang Zhou.

GPUs are much better than CPUs at vector processing-- handling mulitple sets of numeric operations on large arrays of structured data in parallel, explained Nathan Brookwood, Research Fellow with market-analysis firm Insight 64. They can thus offer considerably more performance than CPUs.

Generally, mainstream general-purpose CPUs offer a peak performance between 20 and 150 Gflops, while mainstream GPUs perform between 500 and 1,500 Gflogs, he said.

GPUs have been used to accelerate general programs for several years, and researchers are looking for ways to improve the process. The chips are fast in part because they process data in parallel. They thus mus work with applications written to compute this way.

A key challenge is managing parallelism so that the chips stay busy by efficiently handling various threads they work with. Also challenging, are the effective use of on-chip and off-chip memory, and the even distribution of off-chip memory access to avoid over using memory controllers while leaving others idle.

Zhou's tool compiles the application code optimally to both manage parallelism and efficiently utilize GPU memory. It enables a single memory access to load what would otherwise be multiple memory accesses, which makes data loading quicker and more efficient, thereby improving performance.

The tool then checks the code to determine if it can handle high-performance memory features such as memory coalescing, which lets a GPU efficiently handle memory-access requests from multiple threads in a single process. If so, the tool recompiles the code so that it can implement these features. It subsequently determines whether data can be reused within and across threads. If so, the tool stores data in on-chip shared memory for fast reuse.

Finally, Zhou explained, the tool recompiles the code so that when system accesses off-chip memory, the accesses are evenly and efficiently distributed among multiple memory controllers.

Zhou said tests by his research team showed that programs automatically translated by the new tool operated more efficiently than those manually optimized.

Brookwood said the North Carolina State tool works similarly to Nvidia's CUDA and AMD's ATI Stream Technology, proprietary applications that enable GPUs to accelerate genreral-computing operations. It appears that Zhou's technique optimizes code more aggressively, he noted. Also, because the approach is not proprietary, it works with any hardware platform.

According to Zhou, his approach is more efficient because it yields optimized code that is better at parallelism management and memory utilization.

He said he eventually plans to release his tool as open source software.

Freakonomics Trailer

2010-12-05T05:27:00.000-06:00

This is one of the books I want to read-- Freakonomics (2005 non-fiction book) from authors Steven D. Levitt and Stephen J. Dubner. Yes, I have been in the engineering game for awhile. Sometimes you just loose site of the little-things, like economics. Economics, is the founding factor on which our nation is based upon (capitalism).

Wikipedia gives the following overview:

The book is a collection of 'economic' articles written by Levitt, an expert who has already gained a reputation for applying economic theory to diverse subjects not usually covered by "traditional" economists; he does, however, accept the standard neoclassical microeconomic model of rational utility-maximization. InFreakonomics, Levitt and Dubner argue that economics is, at root, the study of incentives. The book's topics include:
Chapter 1: Discovering cheating as applied to teachers andsumo wrestlers (See below)

Chapter 2: Information control as applied to the Ku Klux Klanand real-estate agents

Chapter 3: The economics of drug dealing, including the surprisingly low earnings and abject working conditions ofcrack cocaine dealers

Chapter 4: The controversial role legalized abortion may have played in reducing crime. (Levitt explored this topic in an earlier paper entitled "The Impact of Legalized Abortion on Crime.")

Chapter 5: The negligible effects of good parenting on education

Chapter 6: The socioeconomic patterns of naming children

One example of the authors' use of economic theory involves demonstrating the existence of cheating among sumo wrestlers. In a sumo tournament, all wrestlers in the top division compete in 15 matches and face demotion if they do not win at least eight of them. The sumo community is very close-knit, and the wrestlers at the top levels tend to know each other well. The authors looked at the final match, and considered the case of a wrestler with seven wins, seven losses, and one fight to go, fighting against an 8-6 wrestler. Statistically, the 7-7 wrestler should have a slightly below even chance, since the 8-6 wrestler is slightly better. However, the 7-7 wrestler actually wins around 80% of the time. Levitt uses this statistic and other data gleaned from sumo wrestling matches, along with the effect that allegations of corruption have on match results, to conclude that those who already have 8 wins collude with those who are 7-7 and let them win, since they have already secured their position for the following tournament.
The authors attempt to demonstrate the power of data mining. Many of their results emerge from Levitt's analysis of various databases, and asking the right questions. Authors posit that various incentives encourage teachers to cheat by assisting their students with multiple-choice high-stakes tests. Such cheating in the Chicago school system is inferred from detailed analysis of students' answers to multiple choice questions. But first Levitt asks, "What would the pattern of answers look like if the teacher cheated?" The simple answer: difficult questions at the end of a section will be more correct than easy ones at the beginning.

Recommended by some friends. I hope to check this book out over the winter break.

Testing the Waters of Game Design

2010-12-03T18:55:00.000-06:00

Obviously, I enjoy a good game. In particular, I enjoy playing Team Fortress 2, Counter Strike, Star Craft 2, Left 4 Dead 2, or really anything.

On my common server that I play on, 2Fort2Furious (http://forums.2f2f.net/), some of the players have a particle effect around their hats. Today, I had a crazy idea-- create new particles for hats for Team Fortress 2.This has already been done, however I do not know how to do it. So, my engineering reflexes kicked in--- and I Googled it.

Here is some of my preliminary findings from FPSBANANA found here (http://www.fpsbanana.com/tuts/10318).

How to Test Out Particle Effects on Any Hat (that you own)!

Tools:
GCFScape or GCFExplorer
Notepad, Notepad++ or any other .txt editor
Team Fortress 2
Basic knowledge

Steps:
1. Open up GCFScape and navigate to your Steam\steamapps directory.
2. Open "team fortress 2 content.gcf"
3. Within the GCF, navigate to tf\scripts\items and extract items_game.txt somewhere. Preferably somewhere that's easy to access (like your desktop).
4. Open up items_game.txt with your text editor.
5. Use ctrl + F to find a hat you'd like to make unusual.
6. Add the following line to it:
"attributes"
{
"attach particle effect"
{
"attribute_class" "set_attached_particle"
"value" "10"
}
}
7. Substitute the "10" with the value of the particle you want to be used.

1 = burningplayer_red
2 = burningplayer_flyingbits
3 = particle_nemesis_burst_blue
4 = community_sparkle (given to community contributor's weapons)
5 = halopoint (the glow used on the Cheater's Lament)
6 = superrare_confetti_green (Green Confetti unusual effect)
7 = superrare_confetti_purple (Purple Confetti unusual effect)
8 = superrate_ghosts (Ghosts unusual effect)
9 = superrare_greenenergy (Green Energy unusual effect)
10 = superrare_purpleenergy (Purple Energy unusual effect)
11 = superrare_circling_tf (Circling Logo unusual effect)
12 = superrare_flies (Flies unusual effect)
13 = superrare_burning1 (Burning Flames unusual effect)
14 = superrare_burning2 (Scorching Flames unusual effect)
15 = superrare_plasma1 (Searing Plasma unusual effect)
16 = superrare_plasma2 (Vivid Plasma unusual effect)
17 = superrare_beams1 (Sunbeams unusual effect)
18 = superrare_circling_peacesign (Peace Sign unusual effect)
19 = superrare_circling_hearts (Circling Heart unusual effect)

8. Save the resulting file in your Steam\steamapps\stevethegamerist\team fortress 2\tf\scripts\items directory.

9. Boot up TF2 and try it out! It only works in offline mode, obviously. But you can check out how different hats look like!

10. This can also be used to apply effects to weapons in thirdperson (not on viewmodels)! Awesome!

Also, here are some pictures of the process...

Adventures of a Curious Mind

Design Patterns - Java

What is inheritance?

What is main for?

What is encapsulation?

How to hide the data?

Instance & Local Variables?

Is A?Versus has A?

When to use Inheritance?

Best Java Interview Review I've found yet! And SOAP vs REST.

Definitions

REST

SOAP

Why REST?

Why SOAP?

WS-Security

WS-AtomicTransaction

WS-ReliableMessaging

Summary

Embedded / Firmware Interview Review

Preprocessor

Infinite Loops

Data declarations

Static

Const

Bit Manipulation

Accessing fixed memory locations

Interrupts

Code Examples

Typedef

Obfuscated syntax

What is the need for an infinite loop in Embedded systems?

How does combination of functions reduce memory requirements in embedded systems?

A vast majority of High Performance Embedded systems today use RISC architecture why?

Why do we need virtual device drivers when we have physical device drivers?

What is the need for DMAC in ES?

What is Endianness of a system and how do different systems communicate with each other?

How are macros different from inline functions?

What could be the reasons for a System to have gone blank and how would you Debug it?

Explain interrupt latency and how can we decrease it?

How to create a child process in linux?

EG Chance's Quake Bible

Introduction

Discipline. (Willing forward the strongest formula)

Presence. (Remaining in the moment to maximize mental efficiency)

Opponent Awareness/Enemy Status. (Mastering the raw data.)

Resource Timing (Expanding and controlling your advantages)

Aim (The most overthought skill in Quake.)

Motivation, Attitude (Pushing the limits)

Resolve. (Conscious adaptation)

Sound 101

Embedded Systems Interview Review

What is the need for an infinite loop in Embedded systems?

How does combination of functions reduce memory requirements in embedded systems?

A vast majority of High Performance Embedded systems today use RISC architecture why?

Why do we need virtual device drivers when we have physical device drivers?

What is the need for DMAC in ES?

What is Endianness of a system and how do different systems communicate with each other?

How are macros different from inline functions?

What could be the reasons for a System to have gone blank and how would you Debug it?

Explain interrupt latency and how can we decrease it?

How to create a child process in linux?

Significance of watchdog timer in Embedded Systems

If you buy some RTOS, what are the features you look for in ?

Why is java mostly used in embedded systems?

Differentiate between mutexes vs semaphores

What are the commonly found errors in Embedded Systems?

What is the need for having multibyte data input and output buffers in case of device ports?

What is lst file?

How is a program executed’ bit by bit’ or’ byte by byte’?

Explain DB.

What is EQU?

How are labels named in assembly language?

Are all the bits of flag register used in 8051?

Which bit of the flag register is set when output overflows to the sign bit?

Which register bank is used if we use the following instructions SETB PSW.3 A SETB PSW.4 B

Issues related to stack and bank 1.

Explain JNC.

Write a program to toggle all bits of P1 every 200ms.

Can port 0 be used as input output port?

Which register bank is used if we use the following instructions
SETB PSW.3 A
SETB PSW.4 B