Components of a Computer
1.
Input/output
(I/O) Unit : - a) Input Unit-It is a device that
is used to give required
information to the computer.e.g. Keyboard, mouse, etc.
b) Output Unit- It is mainly used to display the desired
result to the user as per input instruction. e.g. Video monitor, printer and
plotter, etc
.
2.
Central
Processing Unit (CPU): -It
is a set of registers, arithmetic and control circuits, which together
interpret and execute instructions and assembly language.
·
The
CPU executes the instructions in the stored sequence.
·
The
CPU transfer instructions and input data from main memory to registers i.e. internal
memory.
·
When
necessary, CPU transfers output data from registers to main memory.
The CPU consists
of three main subsystems: - Arithmetic Logic Unit (ALU), Control Unit (CU) and
registers.
Arithmetic
Logic Unit (ALU)- It
is used to perform all arithmetic calculation and logical calculation. Logical
unit performs comparison of numbers, letters and special characters. ALU uses
registers to hold the data that is being processed.
Registers- Registers are special purpose and high speed
temporary memory units. Registers are not referenced by their address, but are
directly accessed and manipulated by the information that the CPU during
execution. Register store data, instructions, address and intermediate results
of processing.
Control
Unit (CU)- Control
unit organizes the processing of data and instructions. It directs the computer
to carry out stored program instructions by communicating with the ALU and the
registers. The basic function of control unit is to fetch the instruction
stored in the main memory, identify the operations and the devices involved in
it accordingly generate control signals.
3. Memory Unit: - The
memory unit consists of (a) primary memory and (b) secondary memory
a):- Primary
Memory-Primary memory of the
computer is used to store the data and instructions during execution of the
instructions. The primary memory is of two types;
I.
Random
Access Memory (RAM).
II.
Read
Only Memory (ROM).
I.
Random
Access Memory (RAM)-It
directly provides the required information to the processor .It is a volatile
memory. It provides temporary storage for data and instructions. RAM is
classified in two categories .
·
Static
Random Access Memory (SRAM).
·
Dynamic
Random Access Memory (DRAM).
II.
Read
Only Memory (ROM)-It
is used for storing standard processing program that permanently
reside in the
computer. Generally, designers program ROM chips at the time of manufacturing
circuits. ROM is non-volatile memory. It can only be read not
written. It is classified into three
categories
·
Electrically
Erasable Programmable ROM (EEPROM)
·
Erasable
Programmable ROM(EPROM)
·
Programmable
ROM(PROM).
b):-Secondary memory-The
secondary memory stores main larger amounts of data and information
for extended
periods of time. It is non-volatile in nature. It is a permanent storage
device. Some
example of secondary memory device is -1.Magnetic Disks, 2.Optical Disks, 3.Solid
State Disks
1.Magnetic Disks- (a) Hard Disk Drive, (b) Floppy Disk
(c) Memory Stick
.
2. Optical Disks- (a) CD, (b) DVD and (c) Blue-ray Disk.
3.Solid State Disks- Pen/Flash Drive.
Secondary Memory Device and their
Storage Method and Capacity
Secondary
Memory Device
|
Storage
Method
|
Capacity
|
Floppy
Disk(5.25 inch)
|
Magnetic
|
1.2
MB
|
Floppy
Disk(3.5 inch)
|
Magnetic
|
1.44
MB
|
Floppy
Disk(8 inch)
|
Magnetic
|
80-242
KB
|
Magnetic
Tape
|
Magnetic
|
Upto
1 TB
|
Hard
Disk
|
Magnetic
|
Upto
1 TB
|
CD-ROM
|
Optical
|
640-680
MB
|
DVD-ROM
|
Optical
|
4.7
-17 GB
|
Pen-Drive
|
Solid
State
|
1 –
512 GB
|
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