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1.1 Computer:
Computer is an electronic device. The term ‘computer’ originated from compute word that means calculations.
Computer can perform different types of operations with speed and accuracy.
Computer is also known as information processing system. It manipulates information, or data. It has the ability to store, retrieve, and process data.
A computer system consists of two major elements: hardware and software.
1.2 Functional Components of the computer
There are 4 main functional components of computer which are listed below:
a) Input Unit
Collection of input devices in known as input unit. Examples: keyboard, mouse, microphone, trackpad on a laptop, video camera, joystick, Scanner, OCR(Optical Character reader), OMR( Optical mark reader), MICR (Magnetic Ink character reader) etc.
Tasks: read input and convert it into binary form(strings of 0’s and 1’s)
b) Output Unit:
Collections of output devices. Examples: Monitor (LED, LCD, CRT etc), Printers (all types), Plotters, Speaker(s), Visual Display Unit etc.
Used to perform tasks- convert binary data into human understandable form and give output with respect to the output device.
c) CPU(Central Processing Unit)
Consists of CU(Control Unit) and ALU(Arithmetic and Logic Unit)
CU used to control other components of computer by passing control signal to them. CU also performs operations such as extract data from memory unit(RAM), Decode or interpret data(what to do), execute result calculated by ALU.
ALU is used to perform- Arithmetic operations(+,-,*,/,%) and Logical operations(==, >=,<=,!=, logical AND, OR, NOT etc.)
Note: CPU also contains registers to hold data and instruction (taken from RAM or main memory) to perform operations by ALU.
d) Memory Unit:
It is also known as computer memory or primary memory. It is used to store data and instructions in binary form.
Consists of RAM (Random Access Memory) and ROM(READ Only memory).
RAM is also known as volatile memory(Data is erased whenever task is completed or power is cut-off).
RAM is also known as working space where user tasks take place.
RAM is also known as user memory.
ROM is known as non- volatile memory. It means instructions stored in ROM are permanent.
ROM is also known as system memory. It means space used by system for booting up or starting up.
Types of Computers
There are three main categories of computers on the basis on voltage signals they understand, they are:
a) Digital Computer
b) Analog Computer
c) Hybrid Computer
a) Digital Computers:
These types of computers can understand only discrete voltages or digital signals or binary signals.
Digital computer can process binary data. It means first data converted into binary form by input unit and then process it and generate results in also binary form that result will be converted into human understandable form by output unit.
Note: We have only study of digital computers in our syllabus.
Digital Computers can also be categorized in to 3 categories on the basis of purpose, performance and size, they are:
Performance wise:
(1) Specific purpose Computers:
Used to perform particular task or operation.
Instructions are already stored in the memory permanently.
They are not versatile in nature.
Examples: graphic intensive Video Games, traffic lights control system, navigational system in an aircraft, weather forecasting, satellite launch / tracking, oil exploration etc.
(2) General-Purpose computers
Used to perform various operations. So, such computers are also known as versatile computers.
Data and instructions are not stored in memory permanently. What operation we want to perform put data and instructions for that as input at time of executions.
Examples: Personal computers, including desktops, notebooks, smart phones and tablets, are all examples of general-purpose computers.