Notes

What do you mean by ‘Volatility’? Explain RAM and ROM with the concept and term. [HSEB 2059]

2011-05-16T20:34:00.001-07:00

Volatility generally means storage that is temporary. Often that is expressed by the data disappearing when the computer is turned off.

RAM

ROM

It stands for Random

Access Memory.

It stands for Read Only

Memory.

It is also called read/write

or volatile memory.

It is also called dead store/

Field store or non-volatile memory.

It's contents lost if power is

off.

It retains contents if power is off.

RAM is divided into-

Static RAM and

Dynamic RAM

ROM is divided into-

PROM

EPROM

EEPROM

Flash Memory

Costly or expensive

Cheap in price.

Both RAM and ROM comes under primary memory.

Distinguish between batch processing and on-line processing. [HSEB 2059]

2011-05-16T20:07:00.001-07:00

Batch Processing

Online Processing

It is also called deferred

processing or off-line processing

It is also called direct access or

random access processing.

Tasks are stored in the form of

batches and processed each batches

as requirement.

It is a fast processing in which

input devices is directly connected to

computer.

With a logical (block) structural diagram, explain functions of elements of computer system. [HSEB 2060, 61, 62]

2011-05-16T20:00:00.001-07:00

Diagram from book (pg 77) or

FIG: Logical Structural Block Diagram of a Computer.

Input Unit: (a) Accept the data and instructions from the outside world.

(b) Convert it to a form that the computer can understand.

Arithmetic and Logic Unit: (a) It accepts operands from registers.

(b) It performs arithmetic and logical operations.

Control Unit: (a) It gives command to transfer data from the input device to the memory and to ALU.

(b) It also transfers result from ALU to memory and to output devices.

(d) It supplies required data and instructions from the memory to ALU.

Memory Unit: (a) All the given instructions data and the results are stored during processing period.

(b) By using the unique address we can identify the locations of memory.

Output Unit: (a) It is the unit through which all the results are given out by output devices.

(b) The popular output devices are: printers, monitors, sound etc.

Describe the terms spooling and buffering. [HSEB 2060]

2011-05-16T18:50:00.000-07:00

Spooling: It is referred as Simultaneous Peripheral Operation Online. It means to put jobs in a buffer, a special area in memory or on a disk where a device can access them when it is ready. Spooling is useful because devices access data at different rates. The spooling technique is used in multiprogramming environment to offer first chance to the program of higher priority and reduce processor idle time. Each application output files are spooled to separate disk file called spool files and spooling system make queue for output process. The most common spooling application is print spooling.
Buffering: Buffering is the name given to the technique of transferring data into temporary storage prior to processing or output, thus enabling the simultaneous operation of devices.
Swapping: The swapping is a memory management technique applied by Operating systems. Swapping is a technique in which high priority process is swap in main memory and low priority process from main memory to swap out. When high priority process is completed, low priority process is swap in again.

Explain the term hardware interrupts and software interrupts. [HSEB 2060]

2011-05-16T18:49:00.000-07:00

= Interrupt allows the current program to be suspended while a higher priority task is executed. The real time and multi tasking operating system (OS) follows interrupts techniques. There are two types of interrupts:
a) Hardware interrupt (external) and,
b) Software interrupt (internal)
a) Hardware interrupt: A hardware interrupt causes the processor to save its state of execution and begin execution of an interrupt handler. These are initiated through the computer’s interrupt pins by external devices. External or hardware interrupt can further be divided into: (i) Mask able and (ii) Non-Mask able.
b) Software interrupt: Interrupt signals initiated by programs are called software interrupts. Software interrupts arise from illegal or erroneous use of an instruction or data. Software interrupts are called traps or an exception.

What is an operating system? [HSEB 2060]

2011-05-16T18:46:00.000-07:00

= Operating system is an interpreter between user and computer. It is a collection of programs which acts as an interface between computer hardware and the user, and controls the execution of all types of programs.
It performs the following major functions:
(i) Controls and co-ordinates the various resources of a computer, such as memory, secondary storage, input, output devices etc.
(ii) Permits the user to create, print, copy, delete, read and write the files.
(iii) Co-ordinate between software and hardware.
(iv) Preventing the system from unauthorized user, computer viruses etc.
(v) Translating programs from one form in to another form.

What is language translator?

2011-05-16T18:45:00.002-07:00

= Computers are digital devices. All types of commands, data and instructions required to be converted into machine code which is the combination of 0’s and 1’s. So, we give instructions to the computer in a language which is similar to English and easier for us to understand. The computer translates these instructions into the machine language with the help o language translators. Language translators are of three types.
(i) Assembler: An assembler is software that converts programs written in assembly language to machine language.
(ii) Interpreter: An interpreter is software that converts programs written in high level language to machine language code. It converts one instruction at a time.
(iii) Compiler: A compiler is software that converts programs written in high level language to machine code in a single operation.

What is antivirus software?

2011-05-16T18:45:00.001-07:00

= Antivirus software is a software utility which scans the storage devices (hard disk, floppy, pen drive etc) for viruses and tries to remove them if found.

What is computer virus? Write down the types of computer virus.

2011-05-16T18:44:00.000-07:00

= A computer virus is a set of program instructions that attaches itself to a file, reproduces itself and spread to other files. It can corrupt files, destroy data, display an irritating message or otherwise disrupt computer operations.
Viruses can be classified by the types of files they infect.
(i) Boot sector virus
(ii) File infecting virus
(iii) Polymorphic virus
(iv) Stealth virus
(v) Multipartite virus

Write short notes on: (a) System Software, (b) Application Software

2011-05-16T18:43:00.000-07:00

= a) System Software: The software that helps to activate the computer system and provide operating environment for other application software is called system software. Its primary work is to control, integrate and manage the individuals hardware components of the computer system. System software is the basic requirement of a computer system. System software is further classified into:
(i) Operating Systems
(ii) Utility software
(iii) Language Translator
(a) Assembler
(b) Compiler
(c) Interpreter
(iv) Device Driver

b) Application Software: Application software is a set of one or more programs designed to solve a specific problem or do a specific task. These software are developed using High Level Languages in the form of creative project work in the software industries. Application software are further classified into:
(i) Packaged Software
(ii) Tailored Software.

Distinguish between the terms ‘Hardware’, ‘Software’ and ‘Firmware’. [HSEB 2059]

2011-05-16T18:42:00.000-07:00

= Hardware: The physical components of computers are called hardware such as input devices, output devices, processing devices, memory devices etc. It provides shape and size and support software for proper functioning. Registers, CPU, Hard Disk, Floppy Disk, Printers, and Mouse etc which are touchable, visible, replaceable electromechanical and electronic part of computer are hardware.
Software: Software is the collection of program and other associated documents that helps to control, manage and integrate the components of computer system to accomplish a specific task. It is a non-touchable, non viable set of instructions coded in computer languages. It is a vital part of computer, without it computer is nothing. Examples are operating system, compiler and interpreter, application software etc.
Firmware: Firmware is a pre written program that is stored in ROM. It configures the computer and not easily modified by users. The instructions coded in BIOS (Basic Input Output Service) are example of Firmware. Firmware ROM contains loader program to load a program into memory.

What is register? What role do they play in computer?

2011-05-16T18:41:00.000-07:00

= Registers are high-speed memory which is located inside of CPU and serves to keep temporary data.
The role of registry in computer is-
(i) The ALU uses registers to hold data that is being processed.
(ii) It contains settings for low-level operating system components as well as the applications running on the platform.
(iii) The kernel, device drivers, services, user interface and third party applications all make use of the Registry.
(iv) The registry also provides a means to access counters for profiling system performance.
(v) The registry contains two basic elements-
a. Keys and
b. Values.

What are the main types of memory in a computer, and explain how do they differ from one another? [HSEB 2062]

2011-05-16T18:40:00.000-07:00

= The computer memory is a data storing devices used to either temporarily or permanently store data or instructions to be processed.
Computer memory is broadly categorized into two. They are-
(a) Primary Memory (Main Memory)
(i) RAM (Random Access Memory)
(ii) ROM (Read Only Memory)
(iii) Cache Memory
(iv) Virtual Memory
(b) Secondary Memory
(i) Hard Disk
(ii) Floppy Disk
(iii) CD-ROM etc.
a) Primary Memory: Though the CPU has calculating capability, it needs some space in which it can actually store the data or to perform calculation. This space in computer is called primary memory.
(i) RAM: It is a temporary memory which holds the data and programs during execution. The user can write, modify, erase and read the data. It is electrically dependent and the data is lost incase of power failure. Hence it is also called as volatile memory.
(ii) ROM: It is a permanent memory that holds the data necessary for the computer to become ready. The user can only read the stored data but cannot write, erase or modify the data. It is electrically independent and the data is not affected by the power failure. Hence, it is called non-volatile memory.
(iii) Cache Memory: Cache memory is used in between the CPU and the RAM and hold the most frequently used data or instructions to be processed. There are three different grades of cache. Some systems will have Level 1 and Level 2. More advanced systems will include the Level 3.
(iv) Virtual Memory: The memory which is not actually present but virtually available to support execution of large program is called virtual memory. Virtual memory combines your computer’s RAM with temporary space on your hard disk.

What is bus in computer architecture? [HSEB 2059]

2011-05-16T18:39:00.000-07:00

= [Better to draw figure from book.]
The bus is a medium used to transfer data and controls from one part to other part of computers. Data is normally transferred between main storage and the processor along a device called a bus which is effectively a means of sending multiple bits of data in parallel.
There are mainly three types of bus:
(a) Data bus,
(b) Address bus,
(c) Control bus,
a) Data bus: (i) A bus which carries a word or a data to or from memory is known as data bus.
(ii) The data width is 8 in 8085, 16 in 8086 and 32 in 80386.
(iii) Data lines are bidirectional.
(iv) One part of the data bus runs between RAM and the microprocessor.
(v) Another part of the data bus runs between RAM and various storage devices.

b) Address bus: (i) The address bus carries memory address.
(ii) The address lines can be 16 in 8085, 20 in 8086 and 32 in 80386.
(iii) It is unidirectional, the bits flow in only one direction.

c) Control bus: (i) The control bus carries the control signals between the units of computers.
(ii) The signals like READ/WRITE, START/HALT etc are carried by a control bus.

Write the importance of primary and secondary storage in computer system. [HSEB 2058]

2011-05-16T18:38:00.002-07:00

= The primary storage or the memory is called the main memory in computer system. It is also known as system memory. Primary storage or memory stores data and programs temporarily during the operation of computer.
There are two types of primary memory. They are Random Access Memory (RAM) and Read Only Memory (ROM). Flash memory and cache memory are also the types of primary memory. These memories have great effect on processing speed of computer. The main function of main memory is READ, WRITE and CLEAR.
In memory hierarchy, it is placed in highest position due to high speed, high cost and small size. Processor directly access primary memory.
A memory, which stores data and programs for a long period of time, is called secondary memory. This memory can also be called backup storage memory or mass storage media. Although it is placed in lower position due to low speed, low cost and large size, it has a very large storage capacity.
Floppy disk, Hard Disk, CD-ROM, DVD, Zip Disk, magnetic tape etc are secondary memories used to store data. Now-a-days, operating system and other software, business data and information are stored in CD-ROM.

What is computer system? Explain.

2011-05-16T18:38:00.001-07:00

= The term “computer system” usually refers to a computer and all of the input, output and storage devices that are connected to it.
Computer system will include the computer along with any software and peripheral devices that are necessary to make the computer function. Every computer system requires an operating system.

Differentiate between impact and non-impact printer. [HSEB 2062]

2011-05-16T18:35:00.001-07:00

Impact Printer	Non-impact printer
Text or image is formed in contact of paper and the printer head.	Text or image is formed without any physical contact of the paper and the printer head.
Noisy, slow and poor quality output.	Noiseless, fast and high quality output.
These printers are cheap.	These printers are expensive.
Example – Dot matrix.	Example – Laser and Ink-jet.

What do you mean by storage media? Why CD-ROM are more reliable than floppy diskettes. [HSEB 2057]

2011-05-16T09:50:00.001-07:00

= A data storage system has two components:
(a) Storage medium (media), and
(b) Storage device.
a) Storage medium is the disk, tape, CD, DVD, paper, or any other substance that contains data.
b) A storage device is the mechanical apparatus that records and retrieves data from a storage medium. E.g. FDD, HDD etc.
In computers, a storage medium is any technology used to place, keep and retrieve data. Storage media is the plural form of storage medium.
CD-ROM is more reliable than floppy disk because CD-ROM stores more data than a floppy disk. The data stored on the CD-ROM cannot by changed by the user. It can store a large volume of data up to 650 MB, whereas the storing capacity of floppy disk is 1.44 MB.

What do you mean by the term computer resolution? Explain.

2011-05-16T09:49:00.000-07:00

= In computers, resolution is the number of pixels contained on a display monitor, expressed in terms of the number of pixels on the horizontal axis and the number on the vertical axis. The sharpness of the image on a display depends on the resolution and the size of the monitor. The same pixel resolution will be sharper on a smaller monitor and gradually lose sharpness on larger monitors because the same number of pixels is being spread out over a larger number of inches.
A display system that supports a maximum resolution of 1280 by 1023 pixels may also support 1024 by 768, 800 by 600 and 640 by 480 resolutions. Display resolution is not measured in dots per inch as it is usually with printers. However, the resolution and the physical monitor size together do let you determine the pixels per inch.

What do you mean by input unit? Explain

2011-05-16T09:48:00.000-07:00

= The input unit of the computer system is used for feeding data and instructions to the computer. These data and instructions given to the computer are called as input and the devices used for giving input are called input unit or devices.
A computer consists of an I/O system. It is used by a person to communicate with a computer. For instance, a keyboard or a mouse may be an input device for a computer, while monitors and printers are considered output devices for a computer.
In computer architecture, the combination of the CPU and main memory is considered the brain of a computer, and from that point of view any transfer of information from or to that combination is considered I/O.
Hence, the devices that are used to input data to the computer are called input unit or devices. The input devices of computer are keyboard, mouse, MICR, OCR, scanner, joystick, trackball etc.

What is a purpose of MODEM and where it could be used? [HSEB 2059]

2011-05-16T09:30:00.001-07:00

= Modem is used to establish an Internet connection using a standard telephone line. It is an electronic device used to convert digital signal into analog and vice versa. Basically, a modem is used for transmitting and receiving data over a communication channel, such as twisted-pair telephone lines, coaxial cables, and optical fibers.
Modem has two parts – (a) Modulator and
(b) Demodulator.
a) Modulator: It converts digital signal into analog.
b) Demodulator: It converts analog signal onto digital.
It is also I/O device because it convert input signal into digital and output signal into analog. There are two types of modem in used, (a) Internal modem and
(b) External modem.

Define (a) MICR, (b) OMR, (c) OCR, (d) OBR

2011-05-16T09:28:00.000-07:00

a) MICR: MICR is a character recognition technology used primarily by the banking industry to facilitate the processing of cheques. The human readable characters are printed on documents using a magnetic ink. It stands for Magnetic Ink Character Recognition.
b) OMR: OMR which stands for Optical Mark Recognition is the process of gathering data with an optical scanner by measuring the reflectively of light at predetermined positions on a surface.
c) OCR: OCR stands for Optical Character Recognition. OCR is the recognition of printed or written text characters by a computer. It is the application software that allows a computer to recognize printed or written characters, e.g. letters, numbers, punctuation marks, and pictograms using an optical scanner for input. OCR is being used by libraries to digitize and preserve their holdings.
d) OBR: It stands for Optical Bar Code Reader which is used for reading bar-coded data. It scans a set of vertical bars of different width for specific data and is used to read tags. Bar code reading is done by a light pen or scanner connected to a computer.

Write short notes on touch pads and light pens. [HSEB 2060]

2011-05-16T09:26:00.000-07:00

a) Touch pads: Touchpad is a flat surface or the screen with touch sensitive points or programs icons. When specific point or icon is touched by finger tips, related program or prompts are activated. It is also called a track pad. Touch pads are usually in laptop which acts as a mouse.
b) Light pens: Light pen is an input pointing device used to draw diagram on VDU (Visual Display Unit) directly. It is connected with VDU. The tip of pen contains light sensitive element which provides a very precise pointing capability directly on the screen. It is used in engineering drawing, architect design, circuit design and other several graphics and art works. It is also used as pointing device for menu displayed on VDU like as mouse.

What is the difference between a microcomputer and a minicomputer?

2011-01-15T18:04:00.000-08:00

Microcomputer

Minicomputer

A microcomputer is a standard

desktop computer used at a

home and in business.

Minicomputers are mid-sized

computer used in universities,

research labs and small corporations.

A microcomputer is a computer

with a microprocessor as its CPU.

Minicomputers are faster than

microcomputers.

They are cheap, compact and can

be easily accommodated on a

study table.

They are expensive and larger than

microcomputer.

Microcomputer is a single-user

computer.

Minicomputer is a multi-user

computer.

The two most common types of

storage devices used with

microcomputers are tapes and

disks.

For secondary storage, most

minicomputers use magnetic disks

or tapes.

Microcomputer is not powerful

or as fast as minicomputer

Minicomputer is powerful than

microcomputer but not as super

computer and mainframe computer.

Examples are- Modern computers

like desktop, laptop etc.

Examples are- IBM 9375,

Motorola 68040 etc.

Compare computer on the basis of size and cost.

2011-01-15T18:02:00.000-08:00

Supercomputer: Super computers are the biggest in size, the most expensive in price than any other computer. This computer is not used as a PC in a home neither by a student in a college. Governments specially use this type of computer for their different calculations and heavy jobs. Different industries also use this huge computer for designing their products. It is also used in Hollywood movies for animation purposes.

Mainframe computer: Another giant in computers after the supercomputer is Mainframe, which can also process millions of instructions per second and is capable of accessing billions of data. It is commonly used in big hospitals, air line reservation companies, and many other huge companies because of its capability of retrieving data in a huge basis. This is normally too expensive and out of reach from a salary-based person who wants a computer for his home.

Mini computer: This computer is next in line but offers less than mainframe in work and performance. These are the computers which are mostly preferred by the small type of business personals, colleges etc.

Microcomputer: Micro computers are also called Personal Computer or PC which are mostly preferred by the home users. These computers are lesser in cost than any other computer. It is small in size and can easily arrange it to fit in your single bedroom with its all accommodation. It is the most popular computer in all.