Computer Fundamental ( BCA SEM-I)

 

CHAPTER-3 COMPUTER COMPONENT

All types of computer follows a same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users

Sr. No.

Operation

Description

1

Take Input

The process of entering data and instructions into the computer system.

2

Store Data


Saving data and instructions so that they are available for processing           as and when required.

3

Processing Data

Performing arithmetic, logical operations on data in order to               convert them into useful information.

4

Output Information

The process of producing useful information or results for the user,         such as a printed report or visual display.

5

Control the workflow

Direct the manner and sequence in which all of the above operations are performed.

INPUT UNIT

This unit contains devices with the help of which we enter data into computer. This unit makes link between user and computer.

The input devices translate the human being information into the form understandable by computer.

CPU (CENTRAL PROCESSING UNIT)

CPU is considered as the brain of the computer. CPU perform all types of data processing operations. It stores data, intermediate results and instructions(program).It controls the operation of all parts of computer.

CPU : CPU is considered as the brain of the computer.

  • CPU performs all types of data processing operations.
  • It stores data , intermediate result  and instructions(program).
  • It controls the operation of all parts of computer.

CPU itself has following three components.

  • Memory Or Storage Unit:
  • Control Unit
  • ALU(Arithmetic Logic Unit)

MEMORY/ STORAGE UNIT:

This unit can store instruction, data and intermediate results. This unit supplies information to the other units of the computer when needed. It is also known as internal storage unit or main memory or primary storage or Random access memory(RAM).

Its size affects speed, power and capability. There are primary memory and secondary memory two types of memories in the computer. Function of Memory Unit are:

  • It stores all the data to be processed and the instructions required for processing.
  • It stores intermediate results of processing.
  • It stores final results of processing before these results are released to an output device.
  • All inputs and outputs are transmitted through main memory.

CONTROL UNIT

This unit controls the operations of all parts of computer. It does not carry out any actual data processing operations.

Functions of this unit are

  • It is responsible for controlling the transfer of data and instructions among other units of a computer.
  • It manages and coordinates all the units of the computer.
  • It obtains the instructions from the memory, interprets them and directs the operation of the computer.
  • It communicates with Input/Output devices for transfer of data or results from storage.
  • It does not process or store data.

ALU(ARITHMETIC LOGIC UNIT)

This unit consists of two subsection namely

  • Arithmetic section
  • Logic Section

Arithmetic section

Function of Arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication and division. All complex operations are done by making repetitive use of above operations.

Logic Section

Function of logic section is to perform logic operations such as comparing, selecting, matching and merging of data.

TERMINAL QUESTION

1)      Write the short notes of the following.

a.       CPU

b.      Control Unit

c.       ALU

2)      What are differences between volatile and non volatile memory.

3)      Distinguish between bit and byte.

4)      How many types of memory? Write the differences between them.

5)      What is Register?

6)      Fill in the blanks with appropriate answers:

a)      The input device that enables you to enter drawing and sketches into a computer is ______________

b)      An example of a non-impact printer is ____________________

c)      _____________ is a program that translates source code into object code.

d)     Viruses that attach themselves to other programs are known as ______________

e)      To create form letters, enveloped and labels you can use the _______features.

 

CHAPTER -4 COMPUTER INPUT DEVICE

Following are few of the important input devices which are used in Computer Systems

·         Keyboard

·         Mouse

·         Joy Stick

·         Light pen

·         Track Ball

·         Scanner

·         Graphic Tablet

·         Microphone

·         Magnetic Ink Card Reader(MICR)

·         Optical Character Reader(OCR)

·         Bar Code Reader

·         Optical Mark Reader

KEYBOARD

Most common and very popular input device is keyboard. The keyboard helps in inputting the data to the computer. The layout of the keyboard is like that of traditional typewriter, although there are some additional keys provided for performing some additional functions.

Keyboard are of two sizes 84 keys or 101/102 keys, but now 104 keys or 108 keys keyboard is also available for Windows and Internet.

The keys are following

Sr. No.

Keys

Description

1

Typing Keys

These keys include the letter keys (A-Z) and digits keys (0-9) which are generally give same layout as that of typewriters.

2

Numeric Keypad

It is used to enter numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid out in the same configuration used by most adding machine and calculators.

3

Function Keys

The twelve functions keys are present on the keyboard. These are arranged in a row along the top of the keyboard. Each function key has unique meaning and is used for some specific purpose.

4

Control keys

These keys provides cursor and screen control. It includes four directional arrow key. Control keys also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).

5

Special Purpose Keys

Keyboard also contains some special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen.

MOUSE

Mouse is most popular Pointing device. It is a very famous cursor-control device. It is a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU on pressing the buttons.

Generally it has two buttons called left and right button and scroll bar is present at the mid. Mouse can be used to control the position of cursor on screen, but it cannot be used to enter text into the computer.

Advantages

·         Easy to use

·         Not very expensive

·         Moves the cursor faster than the arrow keys of keyboard.

JOYSTICK

Joystick is also a pointing device which is used to move cursor position on a monitor screen. It is a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket. The Joystick can be moved in all four directions.

The function of joystick is similar to that of a mouse. It is mainly used in Computer Aided Designing(CAD) and playing computer games.

LIGHT PEN

Light pen is a pointing device which is similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. It consists of a photocell and an optical system placed in a small tube.

When light pen's tip is moved over the monitor screen and pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU.

TRACK BALL

Track ball is an input device that is mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer can be moved.

Since the whole device is not moved, a track ball requires less space than a mouse. A track ball comes in various shapes like a ball, a button and a square.

SCANNER

Scanner is an input device which works more like a photocopy machine. It is used when some information is available on a paper and it is to be transferred to the hard disc of the computer for further manipulation.

Scanner captures images from the source which are then converted into the digital form that can be stored on the disc. These images can be edited before they are printed.

DIGITIZER

Digitizer is an input device which converts analogy information into a digital form. Digitizer can convert a signal from the television camera into a series of numbers that could be stored in a computer. They can be used by the computer to create a picture of whatever the camera had been pointed at.

Digitizer is also known as Tablet or Graphics Tablet because it converts graphics and pictorial data into binary inputs. A graphic tablet as digitizer is used for doing fine works of drawing and images manipulation applications.

MICROPHONE

Microphone is an input device to input sound that is then stored in digital form. The microphone is used for various applications like adding sound to a multimedia presentation or for mixing music.

MAGNETIC INK CARD READER (MICR)

MICR input device is generally used in banks because of a large number of cheques to be processed every day. The bank's code number and cheque number are printed on the cheques with a special type of ink that contains particles of magnetic material that are machine readable.

This reading process is called Magnetic Ink Character Recognition (MICR). The main advantages of MICR are that it is fast and less error prone.

OPTICAL CHARACTER READER (OCR)

OCR is an input device used to read a printed text. OCR scans text optically character by character, converts them into a machine readable code and stores the text on the system memory.

BAR CODE READERS

Bar Code Reader is a device used for reading bar coded data (data in form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books etc. It may be a hand held scanner or may be embedded in a stationary scanner.

Bar Code Reader scans a bar code image, converts it into an alphanumeric value which is then fed to the computer to which bar code reader is connected.

OPTICAL MARK READER (OMR)

OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice questions.

TERMINAL QUESTION

Q1.      Give short notes on the following:

a.       Versatility

b.      Storage

c.       Babbage’s Analytical Engine

d.      Von- Neumann Architecture             

Q2.      Explain MICR, OCR, and OMR

 




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