● The Term “Computer” is derived from latin word “Computare” which means to Calculate.
iii) Barcode Reader ,It is used for reading printed bar codes available on product to be sold.
iv) Optical Mark Reader, It is used to read the answer of objective type tests, voting applications and other evaluation studies.
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● A computer is an electronic machine that accept data ( input ) from the user, process the data by performing calculations and operation on it and then, generate the desired result (output) to the user.
● Charles Babbage also known as father of Computer, who invented the analytical engine and different engine.
● Alan turning is the father of modern computer.
● Abacus is the first mechanical calculator device.
● Pascaline was a first mechanical adding machine.
● ENIAC was a first electronic digital computer. ENIAC stands for Electronic Numerical Integrator and Computer.
Classification of Computer
◆ Based on Size
1. Micro - computers They are the least powerful, yet the most widely used and fastest growing type of computers and are also called portable computers.
e.g. laptop, personal computer, Tablet computer, handheld computer, personal digital assistant ( PDA ).
2. Mini Computer They are smaller in size, faster, cost lower than mainframe computers. Initial designed for engineering and CAD calculation but now used has a central computer which is known as server.
3. Mainframe computer They have large internal memory storage and comprehensive range of software.
e.g. IBM 370 , IBM S / 390 , and UNIVAC 1110 etc.
4. Super Computers They are the fastest and most expensive machine which have high processing speed. e.g. CRAY 1 , PARAM etc. First Super Computer in India in PARAM 8000.
◆ Based on Work
1. Analogue computers They are job oriented computer. They can perform several mathematical operations simultaneously.
e.g. speedometer, seismograph etc.
2. Digital computer They work by calculating binary digits. They perform mathematical calculation and also produce desired graphs, sounds.
e.g. Desktop ( PC )
3. Hybrid computer They are the combination of analogue and digital computer. Machine used in hospital like ECG and DIALYSIS are the commonly used hybrid computers.
◆ Best on purpose
1. General purpose computer They are used to solve variety of problem by changing the program or instructions.
e.g. To make a small database, calculation, accounting etc.
2. Special purpose computer They are used to solve a signal and dedicated type of problem.
e.g. Automatic aircraft landing, multimedia computers etc.
● Component of computer
A computer consists of following main component.
1. Input Units :- An input unit or device can be defined as the electro mechanical device that allows the user to feed data into the computer for analysis and storage to the computer.
Some of the commonly used input device are :-
i) Keyboard uses and arrangement of buttons and keys.
ii) Pointer device It is used to communicate with the computer by pointing to the location on the monitor. e.g. mouse , trackball , joystick , light pen.
v) Optical Character Recognition, It is widely used to convert books and document into electronic files.
vi) Magnetic Ink Character Recognition , It is used by the banking industry to facilitate the processing of Cheque.
vii) Biometric sensor, It is used to recognise physical or behavioral traits of an individual.
viii) Scanner It allow a user to make a image or text and convert it into a digital file.
ix) Microphone It converts the received sound into computer format.
x) Webcam It can be used for video conferencing or online chatting etc.
xi) Digit ( graphic tablet ) It allow one to hand draw image and graphics, similar to the way one draw image with a pencil and paper.
Note. Ctrl , Shift and Alt are Called Modifier keys.
2. Output unit
An output unit or devices is any piece of computer hardware equipment used to communicate the result of data processing carried out by information processing to the outside world.
Output device are:
i) Monitor It displays soft copy of result e.g.
CRT, LCD, LED, 3D, TFT.
ii) Printers They produce a hard copy of document.
These are are of two types;
a) Impact printer Dot Matrix printer, Daisy printer, line printer, drum printer etc.
b) Non - Impact printer inkjet printer, Thermal printer, Laser printer, Electromagnetic printer, Electrostatic printer, etc
iii) Speaker They are used to listen to music.
iv) Speaks synthesizer It is used to produce sound from text.
Central Processing Unit
It is often called' the brain of computer. It is fabricate has a single Integrated circuit ( IC ) and is also known as micro - processor. Computer cannot work without CPU.
It is consist of following man sub-unit.
i) ALU ( Arithmetic Logic Unit ) It execute all arithmetic and logical operation on the available data.
ii) CU ( control unit ) It direct the computer to carry out stored program instruction by communicating with the ALU and the register.
Memory unit
This unit is responsible to store program or data on a temporary or permanent basis. it has
i) Primary memory It communicate directly with the CPU. It include
a) RAM : Random Access Memory
b) ROM : Read only memory
ii) Secondary memory It Store much larger amount of data and information for extended period of time. This includes CD, DVD, blu-ray disc, pen drive, hard disk drive, flash drive, etc.
Basic unit of memory measurement
1 Bit - Binary Digit ( 0 or 1 )
4 Bits - 1Nibble
8Bits - 1 Byte
1024 Byte - 1 KB ( Kilobyte )
1024 KB - 1 MB ( Megabyte )
1024 MB - 1 GB ( Gigabyte )
1024 GB - 1 TB ( Terabyte )
1024 TB - 1 PB ( Petabyte )
1024 PB - 1 EB ( Exabyte )
1024 EB - 1 ZB ( Zettabyte )
1024 ZB - 1 YB ( Yottabyte )
1024 YB - 1 BB ( Bronto byte )
1024 BB - 1 Geopbyte
Data Representation
It refers those method which are used internally to represent information store in computer. Computer store lots of different type of information has numbers, text, graphics, sound, etc.
Number System
It defines a set of values that is used to represent quantity. Digital computer internally use the binary number system to represent data and perform arithmetic calculations.
The number system generally used by a computer are as follows:
1. Binary Number System This system is very efficient for computer, but not for human. It contains only two unique digit 0 and 1. It is also known as Base 2 system. The computer always calculate input in binary form e.g. ( 10101 )
2. Decimal Number System The number system that we use in our day-to-day life is decimal number system. It consists of 10 digit from 0 to 9. It is also known as Base 10 system or positional number system.
