HI friend in my previous blog i have discussed about the following topics regarding computer. The
following topics are a) introduction to computer , b) what is a computer, c) generation of computer, d) types of computer. i think all of you read the above topic. those who still not read the above topic i give you link of the same. The following link of the above topic are
Today i discussed about the organization of computer or the main parts of a computer. please read the topic very carefully......
COMPUTER ORGANISATION
2.1 INTRODUCTION
In the previous lesson we
discussed about the evolution of computer.
In this lesson we will provide you with an overview of the basic design
of a computer. You will know how different parts of a computer are organised
and how various operations are performed between different parts to do a
specific task. As you know from the previous lesson the internal architecture
of computer may differ from system to system, but the basic organisation
remains the same for all computer systems.
2.2 OBJECTIVES
At the end of the lesson you will be able to:
·
understand basic organisation of computer system
·
understand the meaning of Arithmetic Logical Unit, Control
Unit and Central Processing Unit
·
differentiate between bit , byte and a word
·
define computer memory
·
differentiate between primary memory and secondary memory
·
differentiate between primary storage and secondary storage
units
·
differentiate between input devices and output devices
2.3 BASIC COMPUTER
OPERATIONS
A computer as shown in Fig.
2.1 performs basically five major operations or functions irrespective of their
size and make. These are 1) it accepts data or instructions by way of input, 2)
it stores data, 3) it can process data as required by the user, 4) it gives
results in the form of output, and 5) it controls all operations inside a
computer. We discuss below each of these operations.
1. Input: This is the process of entering data and programs in to the
computer system. You should know that computer is an electronic machine like
any other machine which takes as inputs raw data and performs some processing
giving out processed data. Therefore, the input unit takes data from us to the
computer in an organized manner for processing.
2. Storage: The process of saving data and instructions permanently is
known as storage. Data has to be fed into the system before the actual
processing starts. It is because the processing speed of Central Processing
Unit (CPU) is so fast that the data has to be provided to CPU with the same
speed. Therefore the data is first stored in the storage unit for faster access
and processing. This storage unit or the primary storage of the computer system
is designed to do the above functionality. It provides space for storing data
and instructions.
The storage unit performs the
following major functions:
·
All data and instructions are stored here before and after
processing.
·
Intermediate results of processing are also stored here.
3. Processing: The task of performing operations like arithmetic and
logical operations is called processing. The Central Processing Unit (CPU)
takes data and instructions from the storage unit and makes all sorts of
calculations based on the instructions given and the type of data provided. It
is then sent back to the storage unit.
4. Output: This is the process of producing results from the data for
getting useful information. Similarly the output produced by the computer after
processing must also be kept somewhere inside the computer before being given
to you in human readable form. Again the output is also stored inside the
computer for further processing.
5. Control: The manner how instructions are executed and the above
operations are performed. Controlling of all operations like input, processing
and output are performed by control unit. It takes care of step by step
processing of all operations in side the computer.
2.4 FUNCTIONAL
UNITS
In order to carry out the
operations mentioned in the previous section the computer allocates the task
between its various functional units. The computer system is divided into three
separate units for its operation. They are 1) arithmetic logical unit, 2)
control unit, and 3) central processing unit.
2.4.1 Arithmetic
Logical Unit (ALU)
After you enter data through
the input device it is stored in the primary storage unit. The actual
processing of the data and instruction are performed by Arithmetic Logical
Unit. The major operations performed by the ALU are addition, subtraction,
multiplication, division, logic and comparison. Data is transferred to ALU from
storage unit when required. After processing the output is returned back to
storage unit for further processing or getting stored.
2.4.2 Control Unit
(CU)
The next component of
computer is the Control Unit, which acts like the supervisor seeing that things
are done in proper fashion. The control unit determines the sequence in which
computer programs and instructions are executed. Things like processing of
programs stored in the main memory, interpretation of the instructions and
issuing of signals for other units of the computer to execute them. It also
acts as a switch board operator when several users access the computer
simultaneously. Thereby it coordinates the activities of computer’s peripheral
equipment as they perform the input and output. Therefore it is the manager of
all operations mentioned in the previous section..
2.4.3 Central
Processing Unit (CPU)
The ALU and the CU of a
computer system are jointly known as the central processing unit. You may call
CPU as the brain of any computer system. It is just like brain that takes all
major decisions, makes all sorts of calculations and directs different parts of
the computer functions by activating and controlling the operations.
Personal Computer Configuration
Now let us identify the
physical components that make the computer work. These are
1. Central Processing Unit
(CPU)
2. Computer Memory (RAM and
ROM)
3. Data bus
4. Ports
5. Motherboard
6. Hard disk
7. Output Devices
8. Input Devices
All these components are
inter-connected for the personal computer to work.
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