nextG info

2014-08-18T07:24:00.000-07:00

Glossary

2014-07-31T23:01:00.000-07:00

Glossary

1. Cloud computing : Cloud computing is the delivery of computing as a service rather than a product,wherby shared resources software and indormation are provided to computers and devices as a utility over the network.
2. Blue Ray Disc : It is a optical disc storage medium to supersede the DVD formate.Blue Ray Disc are plastic disc same in size and shape as of CDs and DVDs but contain 25 GB per layer with dual layer disc providing 50 GB.
3. Simputer : It is a self-contained open hardware Linux based handheld computer.
4. DNA Computer : It uses DNA,instead of the traditional silicon based computer technology.
5. Quantum Computer : It uses the quantum mechanical phenomena such as superposition and entanglement to perform operations on data.
6. Tablet PC : It is a laptop PC or Mobile PC,equipped with a stylus and/or tuch screen.
7. Bluetooth : (2.4 GHz Radi Wave) It is an open wireless technology for exchanging data over short distance.
8. iPad : It is a tablet Computer designed and developed by Apple.iPhone-5 has been recently launched by Apple.
9. Netbook : It is a branch of subnotebooks, a small,lightweight and inexpensive laptop suited for general computing and accessing web based application.
10. iPod :It is a line of portable media players created and marketed by Apple Inc.
11. Smart Phone : It is a mobile phone that offers more advanced computing ability and connectivity than a basic feature phone.
12. Pen Drive :It is a small device used to store files and transfer files between USB compatible system.
13. Multimedia : Multimedia is the media that uses multiple forms of information content and information processing(e.g.,text,audio,graphics animation,video) to inform or entertain the user (audience).
14. Wi MAX ( World Wide Inter operatability for Microwave Access) : Wi MAX is a wireless communication standard designed to provide 30 to 40 MB/Sec data rates,with the 2011 update providing up to 1 GB /sec.It is part of fourth generation ,4G of wireless communication technology.
15. Tuch Screen : Tuch Screen is an electronic visual display that can detect the presence and location of a touch within the display area.< br />BIOS(Basic Input Output System) : It refers to the software code run by a computer when first powered on.
16. Cache Memory : It is used by the central processing unit to reduce the average time to access memory.
17. Plug and Play : It is a computer feature that allows the addition of a new device,normally a peripheral,without requiring reconfiguration or manual installation of device drivers.

Virus

2014-07-31T22:58:00.000-07:00

Computer Virus

A virus is a computer programme which attaches itself to and becomes part of another executable programme and thus halts the system by leading to some undesired results.

Some Computer Virus

Year	Name
1971	Creeper
1982	EIK Cloner
1988	The Morris Internet Worm
1990	Melissa
2000	I Love You
2001	Code Red
2001	Nimade
2003	SQL Slammer
2003	Blaster
2004	Sasser
2010	Stuxnet

Some popular Anti-Virus

Trend Micro Anti-Virus
Anti Spyware 2010
Panda Security Anti-Virus Pro 2010
Symantec Nortron Anti-Virus 2010
Kaspersky Anti-Virus Plus
MCA fee Anti-Virus
Avast Anti-Virus
Avira Anti-Virus

Networking

2014-07-31T22:53:00.002-07:00

Networking

Computer networking relates to the communication between a group of two or more computer systems linked together.The network of computers can be classified into LAN,MAN and WAN based upon the area of their connectivity.
Local area Network(LAN) : It is a system in which computers can be inter-connected within a geographical spread of 1 km.All the terminals are connected to a main computer called server.
Metropolitan area Network(MAN) : It is a data network designed for a town or a city.Its main purpose is to share hardware and software resources among the carious users.e.g.,a cable TV network.
Wide area Network(WAN) : In a WAN ,the connected computers are much fat from each other and are connected by telephone lines or radio waves .Such a network may spread across countries.
Social Networking : To interact and communicate with the people accross the globe with the help of online tools i.e.,the applications availables over internet is called social networking and the websites designed specifically for this purpose are known as social networking websites.Major Social networking websites where one can make account ,share information,make friends and communicate are Facebook,Orkut,Twitter,Google+,Linked in,Badoo,Meetup,Ning etc.

Computer Terminology

2014-07-31T22:51:00.001-07:00

Terminology

1. World Wide web(WWW): This is a wrldwide system of interconnected computer files linked to one another on the Internet.
2. Client Server : It is a network architecture which separetes the client from the server.Each instance of the client software can send request to a server or application server.
3. Proxy server : Proxy server is a computer that offers a computer network service to allow clients to make indirect network connections to other network services.
4. Website : a website is a collection of web page ,typically common to a particular domain name or sub-domain on the world wide web or the internet.
5. Uniform Resource Locator : It is the another name for Web address .It is basically a string of characters which refers to a resource on the internet.Tin Berners Lee created the first URL in 1991.
6.Android : Android is an Operating system (OS) to be used for web application in mobile phones.Android is based upon a modified version of Linux Kernel.
7. E-mail : In the e-mail facility,users can send and receive mesage through the computer network ,Provided the receiver has an e-mail address.A popular protocol for sending e-mail is Simple Mail Transfer Protocol(SMTP) and for receiving it is POP3.

Operating System

2014-07-31T22:48:00.000-07:00

Operating system

All operating system is a software of a series of programmes,which performs varies types of functions .In order to manage and organise files .MS windows,MS DOS,LINUS,UNIX etc. are the example of operating system.

Programming Language

A computer must be given instructions in a programming language that it understands.The only language ,a computer can directly execute is machine language.All first the programmers write the source code in a number of programming language which is further compiled into machine language by the compiler.The example of such programming language are - ALGOL,BASIC,COBOL,LOGO,COMAL,PROLOG,FORTRAN,CC++ etc.

Microsoft Office

Microsoft Office is a proprietary commercial office suite of desktop applications,servers and services for the Microsoft windows and Mac OS X operating systems introduced by microsoft on August 1,1989.It contains Microsoft Word,Microsoft Excel,Micrisoft Power Point,and Microsoft Access.The current versions are office 2010 for Windows,released on June 15,2010;and office 2011 for Mac OSX,released on October 26,2010.Recently microsoft has launched the latest version of MS Windows as 'Windows-8' which is equipped with a lot of features.
MS WORD : MS word is a word processing application and is one of the most important and widely used application found on computer.
MS EXCEL : MS Excel is a spredsheet application written and distributed by microsoft for microsoft windows and Mac OSX.
MS POWER POINT : The application software that can create professional looking visual aids is called presentation grafics software.
MS ACCESS : MS access is a relational database management system from Microsoft that combines the relational Microsoft JET Data base engine with graphical user interface and software development tools.

Internet And Networking

The Internet is the worldwide,publicly accessible system of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol(IP).

Connection

2014-07-31T21:49:00.000-07:00

Connection Keyboard, Mouse, Monitor And Printer To CPU

Connecting mouse:
Mouse has three model of connectors depends on our need they are ps/2 mouse , serial mouse, USB mouse we can connect the mouse to any one of the three port depends on its model.
Connecting keyboard:
Keyboard has two model of connectors depends on our need they are ps/2 keyboard, USB keyboard we can connect the mouse to any one of the two port depends on its model.
Connection monitor:
Monitors are connected to the video port of the CPU this port is also called VGA port typically they will be in blue colour and has 15 pin female end.
Printers:
Printer has two models of connectors depends of our need they are parallel port printer, USB printer we can connect the printer to any one of the two port depends on its model.
1.7.2 Checking Power Supply
The computer gets its power from the external power supply to system through SMPS (Switch Mode Power Supply) which acts as a AC to DC converter and step down the volts to 3 - 12 DC. The external power card is to be connected to the power supply plug in system and Power Supply Fan
Power On/Off Switch
Power Supply Plug
Ps/2 Key Board Port
Ps/2 Mouse Port
Serial Port
Video Port
USB Port
Network Port
Parallel Port
Audio Port
once the power supply on/off switch is switched on and the power switch in the front side of the system is also switched on then the power supply fan must run, if it is not running then there may be a problem of power supply, if it runs properly then we can assure that we got power to our system.

Hardware and Software

2014-07-31T21:46:00.001-07:00

Concept of Hardware and Software

In this section we shall distinguish between hardware and software used in a Computer. There are different types of software and there are several generations.
Hardware
The electronic circuits and mechanical components of a Computer such as hard disk, printers, central processing unit, keyboard, mouse, motherboard and other peripheral devices, which ere tangible in nature, or which can be felt, touched are known as hardware.
Software
Programs namely the list of instructions to be executed by Computer is known as the software of the Computer. There are different: types of software depending on the requirement of user or Computers. Software fails into two general categories: a) System Software b) Application Software Application software
Refers to the programs, which allow the Computer to carry out specific tasks related to the users such as payroll processing, inventory control, or word processing. Application software may be supplied by the Computer manufacture or software vendors, or may be written by programmers.
System software
Controls and coordinates Computer operations, and unifies all of the Computer components into a functional and smooth running system. System software also provides the Computer users with a means of gaining access to the system and its resources. The task of translating instructions into machine code is done by a special set of software called the Compiler. Operating system prepares the computer for use and also controls the different devices attached to the computer. Operating system & Compilers are the example of system software.
Concept of Computing, Data and Information
Data:
Data is a collection of facts, such as values or measurements. It can be numbers, words, measurements, observations or even just descriptions of things in simple words data is a raw fact example. Representing Data in the Computer:
Basic component of Computer like CPU, RAM etc are transistors. These are made of a number of Integrated circuits (ICs), which contain transistors. These transistors set like a two-way switch which can be either on or off. These transistors have just two operating states; either on or off. When a transistor is switched on, it is said to represent the value 1. Conversely, when the transistor is switched off, it is said to represent the value 0. The values 0 and 1 are the only two digits with which Computer works.
Thus all data to be stored and processed in Computers are transformed or represented as sequence of two symbols, one symbol to represent each state. The digits 0 and 1 are represented inside the computer as electrical voltages. The electrical voltages have just two states, or levels, referred to as high and low. Usually the Low voltage represents a value of 0, while the high voltage represents a value of 1.

Memory

2014-07-31T21:41:00.000-07:00

Computer Memory

There are different types of memories, which are used in computer. Primary memory has other names as Main memory or Random Access Memory (RAM), CPU uses it to store or retrieve data and instructions for processing. Secondary Memory or Auxiliary memory is used to store the data and instructions permanently. Hard disk and (floppy disk are the example of secondary memory. Compact Disk Read Only Memory (CD ROM) is also used to store the data permanently but St requires CD writer to store data into it. Cache memory is used to enhance the performance of Computer system.
Main Memory
Data and instructions are required to be stored in main memory from where it can be retrieved by central processing unit for processing results. Main memory serves as a temporary storage area for data and instructions. It is made up of a large number of cells, with each cell capable of storing one bit. The cells may be organized as a set of addressable words, each word storing a sequence of bits. The time to store and retrieve a word is independent of the address of the word. This organization is also called RAM or Random Access Memory. The main memory is very fast. Its storage capacity is in megabytes. Nowadays most of the Computers have minimum of 128 Mbytes of RAM. All the modern computers are now built with semiconductor main memory because of its fast access time, low cost, small physical size and low power consumption. RAM is further classified as either dynamic RAM (DRAM) or static RAM (SRAM)
The larger capacity chips are normally constructed as dynamic RAM because the dynamic RAM requires less number of transistors than the static RAM and hence can be packed more densely on a single chip. Thus dynamic RAM can achieve higher storage density. DRAM is implemented using capacitors which tend to loose their charge with time and need periodic refreshing. So, it needs extra control circuitry. This refreshing process slows down memory access speed slightly. SRAM, on the other hand, does not need any such refreshing circuitry. Thus a SRAM is faster than a DRAM. DRAM is cheaper than SRAM and consumes less power than SRAM.
Secondary Memory
The programs & data that are required to be used again & again are kept in auxiliary or secondary memory. Floppy disk, Hard disk are the examples of it. The present day capacity of Hard disk is 300 Giga bytes. Because of its relatively slow speed auxiliary storage is used for storing programs and data not immediately needed by the Computer. The programs and data are then copied into faster main memory when the Computer is ready to process them. Secondary storage devices are online to the processor. They accept data or program instructions from the processor, retain them, and then write them back to the processor as needed to complete processing tasks. Examples of Secondary memory are floppy disk, hard disk, magnetic tapes, charge-coupled devices, magnetic bubble memories, optical memories etc.
Floppy Disk
The floppy disk gets its name from the fact that it is made out of a flexible plastic material. The plastic base is coated with an iron-oxide recording substance that's similar to the material applied to the plastic ribbon of a magnetic tape. Data are recorded as tiny invisible magnetic spots on this coating. The disk is loaded and rotated inside its envelope tiny electromagnetic heads in the disk reader access the data through the slot in the jacket. A floppy disk is divided into tracks (these are a series of concentre rings on the surface of the disk) and each track is further divided into sectors. The number of tracks that a disk can hold is measured in tracks per inch (tpi) and it is always mentioned on any floppy disk you buy. A diskette is inexpensive and can be erased and reused many times.
Hard Disk
The disk described so far is the type of disks which can be removed from the disk drive and carried from place to place. Some disks however, are built into the computer or a special disk drive. These are fixed disks. They are used in just the same way as removable disks, but tend to be used for storing programs or data which have to be permanently available. Hard disks can store anywhere from 20 MB to more than 40GB. Hard disks are also from 10 to 100 times faster than floppy disk.
Magnetic Tapes
Magnetic tapes are mounted on reels or a cartridge or a cassette of tape to store large volumes or backup data. These are cheaper and since these are removable from the drive, they provide unlimited storage capacity. Since the recording is like that in a tape recorder used in audio systems, information retrieval will be only sequential and not random as in the case of a disk. These are not suitable for online retrieval of data, since sequential searching will take long time. These are convenient for archival storage for backup.
CD-ROM
The CD-ROM (Compact Disk Read Only Memory) is a direct extension of audio CD. CD-ROM players are more rugged and have errorcorrection facility. This ensures proper data transfer from CD-ROM to the RAM of the computer. CD-ROM is written using a CD writer. Information is retrieved from a CD-ROM using a low power laser, which ingenerate in an on optical disk drive unit. In CD-ROMs the information is stored evenly across the disk in segments of the same size. Therefore, in CD-ROMs data stored on a track increases as we go towards outer surface of disk. Thus, the CD-ROMs are rotated at variable speeds for the reading process.
Cache Memory
CPU speed is quite high as compared to the access time of main memory. In many situations, the performance of the processor suffers because of the low speed of the main memory. This problem is solved by placing small fast memory called cache memory between the processor and the main memory whose access time is close to the processing speed of the CPU. Cache memory is faster than the main memory. The cache memories although are fast yet are very expensive memories and are used in only small size. Thus, small cache memories are intended to provide fast speed of memory retrieval without sacrificing the size of memory. Cache memory stores a copy of the instructions and data to be immediately used of main memory. The memory reads or writes operation is first checked with cache memory and if the desired location data is available in cache memory then used by the CPU directly.

Output Device

2014-07-31T21:38:00.000-07:00

Other Output Devices

An output device is a part of the computer system which is used to show results. Output devices convert information from the electronic form used by the Computer into a form that people can easily work with. Output normally can be produced in two ways; either on a display unit or on a paper. Other kinds of output such as speech output, mechanical output are also being used in certain applications. Printer receives data from the Computer and translates the data into a printed document. The same data could also be displayed on the video display unit. The method of output used depends often on whether the user wants the output to be permanent and on paper or not. Let us discuss some of the common output devices.
Display Devices
One of the most important peripherals in computer is the display device. Graphic display is made up of a series of dots called 'pixels' (picture elements) whose pattern produces the image. Each dot on the screen is defined as a separate unit, which can be directly addressed. Since each dot can be controlled individually there is much greater flexibility in drawing pictures. There are three categories of display screen technology;
1. Cathode Ray Tube (CRT)
2. Liquid Crystal Display (LCD)
3. Projection Displays
CRT Displays
The CRT (Cathode Ray Tube) monitor receives video signals from the computer and displays the video information as dots on the CRT screen. The main unit to the CRT monitor is the CRT itself; it is usually called a picture tube. The CRT is an evacuated glass tube with a fluorescent(phosphor) coating on the inner front surface, called screen. An electron gun at one end (neck) emits an electron beam. This beam is directed towards the screen. When the beam strikes the screen, the phosphor coating on the screen produces Illumination at the spot where the electron beam strikes.
The electron beam is deflected by an electromagnetic deflection in order to produce illumination at various spots on the screen. Horizontal deflection coils deflect the beam in the horizontal direction and the vertical deflection coils deflect the beam in the vertical direction. The illumination caused on the screen exists for a few milliseconds due to the persistence of the phosphor. To create a permanent image on the screen, it is necessary to cause illuminations repeatedly. This is done by scanning the CRT screen with the electron beam.

There are two types of CRT displays:

1. Vector CRT displays in which the electron beam is directed only to the places where the image is to be created.
2. Raster Scan displays in which the image is projected on to the screen by directing the electron beam across each row of picture elements from the top to the bottom of the screen, This type of display provides a high dynamic capability since image is continuously refreshed and it allows for continual user input and output. It offers full colour display at a relatively low cost and is becoming very popular.
Liquid Crystal Displays (LCD)
First introduced in watches and clocks in 1970s, LCD is now applied to display devices of a computer. The major advantage of LCD is the low energy consumption. The CRT is replaced by liquid crystal to produce the image. These also have colour capability but the image quality is relatively poor. First introduced in watched and clocks in1970s, LCD is now applied to display devices of a computer. The major advantage of LCD is the low energy consumption. The CRT is replaced by liquid crystal to produce the image. These also have colour capability but the image quality is relatively poor.
Projection Displays
A large screen upon which images are projected replaces the personal size screen of the previous displays. These are normally used for large group presentation. These systems can be connected to computer and whatever appears on the computer terminal gets enlarged and projected on e large screen. Another popular method is to connect computer to an LCD flat screen and to project the LCD image using Overhead Projector. These are popularly used for seminars, classrooms, marketing presentations, etc.
Terminals
Terminal is a combination of Input unit and Output unit like VDU and keyboard. Terminals have become very popular interactive input and output units. With the help of a terminal data and instructions can directly be sent into the computer. Terminals can be classified into two types, namely hard copy terminals and soft copy terminals. A hard copy terminal provides a printout on paper where a soft copy terminal provides a visual display on screen. A soft copy terminal is also known as a CRT (Cathode Ray Tube) terminal. Terminals are also classified as dumb terminals or intelligent terminals depending upon provision for any intelligence or otherwise as the terminal. Current technology has brought about a low price differential between intelligent and dumb terminals. This encourages use of intelligent terminals.
Printers
Printer is a very common and popular output device. It accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheet of paper. Printed output provides permanent record and is easy to copy and distribute. Familiar, computer printed documents include pay slips, Familiar, computer printed documents include pay slips, bank statements electricity bills, etc. Different types of printers with different brand names are available in the market. They vary in size, speed, sophistication, and cost. Generally we divide printers into two categories: impact and non-impact.
Impact Printers
Impact printers are printers that create characters by striking a print page with a print hammer (like in typewriter). The impact printers developed for use with computers work in much the same way as typewriters.
1. Dot Matrix Printer
This is also a character printer. In the dot-matrix printer, an arrangement of tiny hammers strikes to produce the desired characters. Each hammer prints a small dot on the paper.
2. Line Printer
It prints a line at a time. In the line printer, raised characters extend the length of the drum. There are as many bands of type as there are printing positions.. Each band contains all the possible characters. The drum rotates rapidly, and one revolution is required to print each line. A fast acting hammer opposite each band strikes the paper against the proper character as its passes. Thus, in one rotation, hammers of several positions may “fire” when the A row appears, several others may strike to imprint D's, etc. At the end of the rotation, the line has been printed.
Non Impact Printers
As their name implies, non-impact printer employ some process other than hammers or similar"percussion type'' mechanisms to form characters on a print page. It uses techniques such as ink spray, heat, Xerography or laser to form printed copy, i.e., characters are not formed by mechanical impact. Usually, non-impact printers are quieter than impact printer. 1. Inkjet Printer
It is a non-impact character printer. It fires a fine jet of dots of quick drying ink onto the paper to form character or dot graphics by using an electrostatic field. When Continuous stream inkjet printers are used, droplets of ink are electronically charged after leaving a nozzle. The droplets are then guided to the proper position on the paper by electrically charged deflection plates. The print quality is good because the character is formed by dozens of tiny dots.
2. Laser Printers
They are page printers, i.e., print a whole page at a time. Laser printers write the desired output image on a copier drum with a light beam that operates under computer control. A difference in a electric charge is created on those parts of the drum surface exposed to the laser beam. These laser-exposed areas attract a toner that attaches itself to the laser generated charges on the drum. The toner is then permanently fused on the paper with heat or pressure.

Input Device of PC

2014-07-31T21:32:00.002-07:00

The central processing unit (CPU) is where the actual processing takes place. This is where the calculations are performed and logical functions are carried out. The CPU retrieves its data and instructions from the main memory, processes the data according to the instructions and then stores the results back into the main memory or sends the processed information to the output subsystem. There are broadly three parts of Central Processing Unit. Control Unit controls all the operations in computer. All the arithmetic and logic operations are performed in Arithmetic and logic unit (ALU). A set of registers is used for temporarily storing data or instructions in CPU. It is to be noted that the central processor is controlled by the instructions it gets from main memory. The CPU retrieves and executes these instructions one by one until it completes a given task. Each instruction tells the CPU what to do (add, divide, move, and compare) and also tells it where to find the data to be processed. CPU, memory all other components are connected through buses on Motherboard and are housed in a cabinet or system unit. The bus interconnects the different parts of the Computer so that information can move from one part of the Computer to another. In effects, the bus is a "highway'' over which electrical signals can travel. For example when the CPU retrieves an instruction from the main memory the electrical pulses representing that instructions are carried over the bus that connects the CPU and main memory. There are three different types of Buses used in Computer. These are Address bus, Data Bus and Control Bus.

Keyboard, Mouse and VDU

To solve a problem it is necessary to give data and instructions to the Computer. This can be done through input device. The keyboard is an example of an input device that accepts data and translates it into electronic signals. Both program (instructions) and data can be keyed in through it. In addition, certain commands to software can be given from the keyboard.
The keyboard consists of a set of keys. There is one key switch for each letter, number, symbol etc, much like a typewriter. Most common keyboard is called QWERTY keyboard as the alphabets in the first row are placed like commonly used typewriters. When a key is pressed, the key switch is activated. The keyboard has an electronic circuit to determine which key has been pressed. A code is then generated and sent to the computer. For example when you press the alphabet A on the keyboard, it is translated into the electronic code 0100001, which is sent to the Computer. Similarly, the number 0 is translated into the electronic code 00111001. So keyboard is one way to get data into the Computer. Detecting which key is pressed and generating the corresponding code is known as encoding. ASCII (American Symbolic Code for Information Interchange) is one such commonly used code.
Mouse
Mouse is a pointing device which can be moved on a smooth surface to simulate the movement of cursor that is desired on the display screen. Mouse could be optical; offering quite and reliable operation, or mechanical which is cheaper. User can move the mouse; stop it at a point where the pointer is to be located and, with the help of buttons, and make selection of choices. The mouse is not an alternative to the keyboard for entering data. Text and numbers still have to be keyed in, but selection from menus and drawings are easier with a mouse. There are 2 keys, 3 keys and scrolling facilities available in mouse.
VDU
One need to see which key is pressed, and makes changes in case of any mistakes. Whatever one has keyed in gets displayed on the screen of the monitor also known as video display unit (VDU). It is also used to show the Information produced by the computer. Most display screens of a monitor work under the same principle as a television, using a cathode ray tube (CRT). Consequently, the term CRT is often used in place of display screen. There are many ways to classify monitors. The most basic are in terms of colour, its screen size and the resolution. First two types are very explicit. The resolution of a monitor indicates how densely packed the pixel (often expressed in dots per inch) are. In general, the more pixels mean the sharper the image. VGA (video graphics array) or SVGA (Super VGA) monitors are most frequently used Monitors today. Both these terms generally refer to the resolution capabilities of the monitor. Most modern monitor’s can display 1024 by 768 pixels, the SVGA standard. Some high-end models can display 1280 by 1024, or even 1600 by 1200. The older Monitor types were MDA (monochrome display adapter), CGA (colour graphics adapter), and EGA (enhanced graphics adapter). These are now outdated and do not work with newer versions of Windows operating system,

Other Input Devices

Data can be fed into a Computer through input devices. Input devices accept data in its original format and translate the data into electronic signals the Computer can process.
Pointing Devices
While working with display based packages, we are mostly pointing to some area in the display to select an option and move across on the screen to select subsequent options. For such cases pointing devices are very useful. There are several pointing devices, some of them are light pen, track balls and joysticks.
Light Pen
This is a pen shaped device allowing natural movement on the screen. The pen contains the Light receptor and is activated by pressing the pen against the display screen. Receptor is the scanning beam, which helps in locating the pen's position. Suitable system software is provided to initiate necessary action when we locate an area on the display surface with the help of the light pen. There are other pointing devices such as track balls and joysticks, which are used more for entertainment applications like games.
Voice / Speech Input
One of the most exciting areas of research is in recognizing human voices / speech so that this could form input to computer directly. This approach will eliminate the need for keying in data and will facilitate casual users to use the computer very easily. There are several problem areas for research since speech recognition system should be able to identify who is speaking and what the message is. Voice recognition techniques along with several other techniques to convert the voice signals to appropriate words and derive the correct meaning of words are required for a commercially viable comprehensive speech recognition system. We have found limited success in this area and today devices are available commercially to recognize and interpret human voices within limited scope of operation.
Scanners
Scanners facilitate capturing of the information (an image, text document, a drawing or a photograph) and storing them in graphic format for displaying back on the graphical screen. Scanner illuminates the page that is to be scanned so that optical image transforms into digital format for stored in computer. The graphic image scanned can now be seen and processed directly by the computer. Scanners come in handheld, feed-in and flat bed types and for scanning black and white only or colour.
Source Data Automation
We can also collect data directly from different sources rather than typing with the help of different devices. This is called source data automation. Most recent trends for data input are towards source data automation. The equipment used for source data automation captures data as a by product of a business activity thereby completely eliminating manual input of data.

Some examples are:

1.Magnetic Ink Character Recognition (MICR): These devices are generally used by the banking industry to read the account numbers on cheques directly and do the necessary processing.
2.Optical Mark Recognition (OMR): These devices can sense marks on computer readable papers. Academic and testing institutions to grade aptitude tests where candidates mark the correct alternatives on a special sheet of paper use this kind of device. The optical mark recognition devices then directly read these answers sheets and the information sent to a computer for processing. The entrance tests and some of the assignments are being marked by OMR. 3.Optical Bar Code Reader (OBR): These scans a set of vertical bars of different widths for specific data and are used to read tags and merchandise in stores, medical records, library books, etc. These are available as hand held devices.

CPU

2014-07-31T21:26:00.002-07:00

Computer

A computer is an electronic device that can receive a set of instruction or programme,and then carry out this programme by performing calculate on numerical data or by manipulating other forms of information.
What is Computer?
Computer derives its name from the word Compute that means calculation. It can be said that Computer is a device used for calculation. Nowadays Computer is not only limited to computation, but also used for making phone calls, maintaining databases, listening songs, viewing movies etc, so a more formal definition of Computer is required. Computer is an electronic device that processes or transforms data into useful information by executing a series of predefined instructions.
Input---->Processing Unit-->Memory<-- ---->Out Put---->

Generations of Computer

Generation	Period	Main Electronic components	Main computer	Operating system
I	1945-56	Vacuum Tubes,Flip-Flops	UNIVAC,ENIAC	Mainly Batch Operating system
II	1956-63	Translators	IBM-700,IBM-1401	Time sharing Operating system
III	1964-71	Integrated Circuits(ICS)	IBM-1620,ATLAS,ICL-1901,IBM-360,IBM-370	Real Time and Time sharing Operating system
IV	1971-Present	Micro processors(LSI-Large scale Integration)	NCR-395,CDC-1700,Apple,DCM	Time Sharing Networks
V	Present and Beyond	Optical fibre,artificial Intelligence(VLSI and VVLSI-Very Very Large Scale Integration)	-----------	------------

Componants of Computer

2014-07-31T21:22:00.002-07:00

Components of Computer System

Computer

2014-07-31T21:19:00.003-07:00

Computer

Skeleton system

2014-07-30T01:20:00.000-07:00

Skeleton system

The human skeleton consists of both fused and individual bones supported and supplemented by ligaments,tendons,muscles and cartilage.It is divided into two parts :
Axial Skeleton(80 bones):It includes skull,vertebral column and bones of chest.The total number of bones of head 29.The total number of bones in vertbral column,initially 33 and after development 26.
Appendicular Skeleton(126 bones): Their function are to make locomotion possible.

Protozoan diseases

2014-07-30T01:17:00.000-07:00

Protozoan Diseases,Their Vectors and affected Part

Diseases	Pathogen	Vector	Parts affected and symptom
Pyorrhoea	Entamoeba gingivalis	None,infection by lip kissing	Bleeding of gums
African trypanosomiasis	Trypanosoma gambiense	Tse-Tse fly	Blood and nervous tissue.Man feel sleepy,may cause death
Amoebic Dysentery	Entamoeba histolytica	None,infection by contamination	Colon,develop loose motion with blood,pain in abdomen
Diarrhoea	Giardia	None,infection by contamination	Digestive system causes loose motion,vomiting
Kala azar	Leishmania donovani	Send flies	Spleen and liver enlarge and high fever
Filaria	Wuchereria	Culex mosquito	Swelling legs ,testes and other body parts
Malaria	Plasmodium sp	Female Anopheles mosquito	Periodical attacks of high fever,pain in joints,accompanied by chill,heavy perspiration and fast pulse.

Viral disease

2014-07-30T01:14:00.000-07:00

Viral diseases in Human Beings

Disease	Pathogen	Affected Part	Symptom
Measles	Rubella virus	Whole body	Loss of appetite ,reddish eruption on the body
Chicken pox	Vericella virus	Whole body	High fever,reddish eruption on body
Small pox	Variola virus	Whole body	Light fever,eruption of bile on body
Polio	Polio virus	Throat backbone and nerve	Fever,backbone and intestinewall cells are destroyed .It leads to paralysis.
Influenza	Influenza virus	Whole body	Inflammation of upper respiratory tract,nose and eyes.
Rabies	RNA virus called Rabies virus	Nervous system	Encephalitis ,fear of water,high fever,headache,spasm of throat and chest leading to death
Dengue Fever	RNA containing Dengue virus	Whole body,particularly head eyes and joints	High fever,backache,headache,retro-orbital pain behind the eye ball.
Hepatitis	Hepatitis A virus	Liver	Loss of appetite,nausea,whitish stool and jaundice
AIDS	Human Immuno deficiency virus	White Blood cell	Weak Immuno system
Herpes	Herpes virus	Skin	Swelling of skin

Human Becterial Disease

2014-07-30T00:42:00.000-07:00

Bacterial diseases in Human Beings

Disease	Pathogen(Bacteria)	Affected Organ	Symptoms
Tuberculosis	Mycobacterium tuberculosis	Lungs	Repeated caughing high fever
Diphtheria	Corynebacterium diphtheriae	Respiratory tract	Difficulty in respiration(mainly in child of age 2-5 years)
Whooping cough or pertussis	Bacillus pertussis	Respiratory system	Continuous coughing
Cholera	Vibrio cholerae	Intestine	Vomiting,acute diarrhoea,muscular cramps,dehydration etc.
Tetanus(lock jaw)	Clostridium tetani	Central nervous system	Painful contraction of neck and jaw muscles followed by paralysis of thracic muscles
Pneumonia	Diplococcus pneumoniae	Lungs	Sudden chill.chest pain,cough,high fever and lung swelling
Typhoid	Salmonella typhi	Intestine	High fever,diarrhoea,headache and gastro intestinal disorder
Syphilis	Treponema pallidum	Urinary path	Wonds in urinogenital tract.

Human Diseases

2014-07-30T00:39:00.000-07:00

Human Diseases

A disease is a condition of the body or its part in which functions are disterved or deranged.

Endocrine system

2014-07-30T00:33:00.000-07:00

Endocrine system

It includes endocrine or ductless glands.Their secretion is known as hormones.Different type of hormones are :
1.Steroids : e.g.,estradiol,testosterone,androsterone,aldosterone,cortisol,and cortisone.
2.Peptides : insulin,glucagon,pituitary hormones,parathormone and relaxin.
3.Amino acid derivatives : Adrenaline,noradrenaline and thyroid hormones.Pituitary gland is also known as master gland.

Some Endocrine Glands :
Thyroid Gland : It is the largest endocrine gland and situated in neck region.It is the pace setter of the endocrine system .It secretes thyroxine.
Gonads : It secretes steroid hormones.
Ovarian hormones(Oestrogens): It helps in the development of primary and secondary sexual characters.
Testicular Hormones(Androgens) : These are produced by Leydig's cells of testes.It stimulate growth ,maturation and maintenance of male gonads and development of secondary sexual characters,e.g. testosterone,androsterone,etc.

Effect of Deficiency and Excess of Hormones

Thyroxine Secretion : Lower secretion causes cretinism (young),Hashimoto's disease and myxoedema in adult.Higher secretion causes exophthalmic goitre.Lack of iodine in the diet causes goitre.
Parathomone Secretions : Lower secretion causes tetany,Higher secretion causes neurofibromatosis.
Growth stimulating Hormones Secretions : Lower secretion caused Dwarfism in young,Higher secretion caused gigantism in adult.LTH helps formation of crop milk in birds.Let down reflax or milk ejection response.
Insulin Secretion : Lower secretion leads ti diabetes mellitus.Aldosterone hypersecretion causes Conn's syndrome.Cortisol oversecretion causes Cushing's syndrome.

Reproductive system

2014-07-30T00:30:00.000-07:00

Reproductive System

The process by which new individuals are produced from their parents is called reproduction and the organs which are used for this process ,collectively constitute the reproductive system .Reproduction is of two types i.e.,asexual and sexual.In asexual reproduction ,only one parent is involved and sex cells are not involved ,e.g.,frog,hydra etc.In sexual reproduction,two parents are involved and formation and fusion of gametes takes place.

Male Reproduction system

Males can produce spermatozoa(sperm)throughout their life from age of 13-14 years.The various organs which constitute the male reproductive system and their functions are tabulated below.

Reproductive Organ	Number	Function
Testes	2	Produce sperm and testosterone
Sperm duct	2	Conduct the sperm from the testes to urethra
Seminal vesicles	2	Secret seminal plasma
Prostate gland	2	Secret an alkaline fluid to neutralize the acidity of urethra and make the spermative
Penis(urethra)(have rich blood supply)	1	Pass urin and deposite sperm in female genital track

Female Reproductive System

Female reproductive system includes following organs which are tabulated below.

Reproductive Organ	Number	Function
Ovaries	2	To produce ova and hormones
Oviducts	2	To move the ovum towards uterus
Uterus	1	To provide space for developing child
Vagina	1	To receive the sperm

If sperm is present ,the egg will be fertilized in the fallopian tube.After maturity the ovary release on ovum after every 28 days.The connection between developing embryo and mother is by placenta.It supplies blood ,etc.Reproductive period of a human female extends from puberty(10-14 years)to menopause(40-50 years)Menopause is stopping of ovulation and menses .It normally occurs between the ages of 45 and 55 .In this stage,woman lose the ability to reproduce.

Nervous system

2014-07-30T00:26:00.000-07:00

Nervous system

The nervous system provides the fastest means of communication within the body so that suitable response to stimuli can be made at once.Central nervous system consists of brain and spinal cord.The function of some of these parts are as follows :
1.Thalamus deals with pain,presure and temperature.
2.Hypothalamus deals with water balance is body,behavioural patterns of sex,sleep,stress,emotions,etc.It also regulates pituitary hormones and metabolism of fat,carbohydrate and water.
3.Spinal cord deals with impulses to and from the brain and is the centre for reflax actions like blinking of the eye when an object comes near to our eyes suddenly ,Rapid withdrawal of hand while burned,knee jerk reflax ,etc.

Sense Organ

Eye : Eyes are the sensitive detectors of light .The human eye can distinguish about 10 million colours.It consists three parts :
Sclerotic Layer : It is the outermost ,bony layer ,which includes-cornea and conjunctiva.
Choroid Layer : It is the middle layer and consists of
(1)Pupil is the black hole in the centre of the iris.it changes size as the amount of light changes.
(2)Iris is the coloured part of the eye.It controls the amount of light that enters the eye by changing the size of the pupil.
(3)Lens is a biconvex transparent circular solid located just behind the iris .It focuses light onto the retina.
Retina : Light sensitive tissue that lines the back of the eye.It contains millions of Photoreceptors(rod and cones)That convert light rays into electrical impulses that are relayed to the brain via the optic nerve.The image formed on retina is real and inverted.Rods are highly sensitive to dim light.Cones are sensitive to bright light ,hence differentiated the colours.

Eye Defects

Nearsightedness(Myopia) : A condition in which nearby objects are seen more clearly than distant objects because light is focused in front of the retina,not on it.It can be corrected by using concave glasses.
Farsightedness(Hypermetropia) : a condition in which distant objects are seen more clearly than nearby objects because light is focused behind the retina ,not on it.It can be corrected by using convex glasses.
Astigmatism : A condition in which the lens is wraped causing images not to focuse properly on the retina.A cylindrical glasses can correct the defect.

Ear

Ears are meant for both balancing and hearing.Hearing is controlled by auditory area of temporal lobe of cerebral cortex.Human ear can hear the sound of 60-80 decibel.Human ear is sensitive to sound s frequency 50-20,0000 cycles/sec

Excretory system

2014-07-30T00:21:00.001-07:00

Excretory System

The process of removal of nitrogenous wastes from the body is called excretion .The organs of excretion are called excretory organs.

Human Excretory System

The human urinary system includes-the kidneys(two),Ureters(two)Urinary bladder(one)and urethra(one)
Kidney from the urine and controls osmatic pressure within the organism with respect to external environment.
Urin : It is yellow coloured fluid due nto presence of urochrome pigment.It is acidic in nature (pH 6.0) and is slightly heavier than water.It has a faint aromatic odour due to Urinoid.Daily urin output in normal adult is 1.5-1.8 L.Chemical composition of urine water is 95-96%,urea is 2% and some other substance like uric acid,creatinine,etc. are 2-3 %.

Circulatory System

2014-07-30T00:18:00.000-07:00

Circulatory system

It is a transport system to supply the useful material and to remove the wastes from the body cells.

Heart

Heart is a thick muscular,contractile automatic pumping organ of blood vascular system.The chamber which receive s the blood from body tissues are called auricles and the chambers of heart which pump blood to body tissues are called ventricles.
human heart beat is myogenic in nature,i.e.,initiated by a patch of modified heart muscles itself without requiring an external stimulation .This patch is called SA node (sino-auricular)or pacemaker.
When SA node becomes defective,i.e.,it does not generate cardiac impulse ,it can be cured by surgical grafting of an artificial pacemaker(an electric device) in the chest of the patient.It stimulate the heart electrically at regular intervals.

Blood Vessels

Blood vessels are of three types.
1.Arteries : These carry the blood away from the heart to various body parts.These carry oxygeneted(pure) blood in them.except the pulmonary artery which carries de-oxygenated blood to the lungs.
2.Veins : These carry blood away from various body aparts of the heart.These carry de-oxygenated blood in them except the pulmonary vein which carries oxygenated blood to the heart.
3.Capillaries : These are the thinnest blood vessels and connect arteries to the veins.These help in exchange of materials like the nutrients,gases waste products etc.Beyween blood and cells.
Blood : Blood is fluid connective tissue and composed of blood corpuscles,Plasma and plateletes.It is slightly alkaline in nature (pH7.4)Itas volume in an adult in 5.8 L.

Respiratory system

2014-07-30T00:12:00.000-07:00

Human Respiratory system

The human respiratory organs are shown in the following diagram.
Overall passage of air in human is as follows:
Nostrils-->Pharynx-->trachea-->Bronchi-->Bronchioles-->Alveoli-->Cells-->Blood.
Breathing rate in human = 18-20/min.Transportation of oxygen takes place by haemoglobin of blood.Whereas transportation of only 10-20% carbon dioxide takes place by haemoglobin of blood.

nextG info

Glossary

Glossary

Virus

Computer Virus

Some Computer Virus

Some popular Anti-Virus

Networking

Networking

Computer Terminology

Terminology

Operating System

Operating system

Programming Language

Microsoft Office

Internet And Networking

Connection

Connection Keyboard, Mouse, Monitor And Printer To CPU

Hardware and Software

Concept of Hardware and Software

Memory

Computer Memory

Output Device

Other Output Devices

There are two types of CRT displays:

Input Device of PC

Keyboard, Mouse and VDU

Other Input Devices

Some examples are:

CPU

Computer

CONTENTS

Componants of Computer

Components of Computer System

Computer

Computer

Contents

Skeleton system

Skeleton system

Protozoan diseases

Protozoan Diseases,Their Vectors and affected Part

Viral disease

Viral diseases in Human Beings

Human Becterial Disease

Bacterial diseases in Human Beings

Human Diseases

Human Diseases

Endocrine system

Endocrine system

Effect of Deficiency and Excess of Hormones

Reproductive system

Reproductive System

Male Reproduction system

Female Reproductive System

Nervous system

Nervous system

Sense Organ

Eye Defects

Ear

Excretory system

Excretory System

Human Excretory System

Circulatory System

Circulatory system

Heart

Blood Vessels

Respiratory system

Human Respiratory system