06-09-2012, 03:49 PM
COMPUTER ORGANISATION
COMPUTER ORGANISATION.pdf (Size: 160.84 KB / Downloads: 116)
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 organized and how various operations are performed
between different parts to complete a specific task. As you know
from the previous lesson the internal architecture of computer may
differ from system to system, but the basic organization remains the
same for all computer systems.
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.
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. The result is then sent back
to the storage unit.
Output: This is the process of producing results from the data
for getting useful information. The results could either be displayed
on the screen or may be printed for future reference. The
output unit therefore allows the results to be either stored inside
the computer for further processing or may give you the
results in human readable form.
Control: The process of input, output, processing and storage is
performed under the supervision of a unit called ‘Control Unit’.
It decides when to start receiving data, when to stop it, where to
store data, etc. It takes care of step-by-step processing of all
operations inside the computer.
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. These are 1) arithmetic logical unit, 2) control unit,
and 3) central processing unit.
(a) Arithmetic Logical Unit (ALU)
After you enter data through the input device it is stored in the
primary storage unit. Arithmetic Logical Unit performs the actual
processing of data and instruction. 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.
MEMORY SYSTEM IN A COMPUTER
There are two kinds of computer memory: primary and secondary.
Primary memory is an integral part of the computer system and is
accessible directly by the processing unit. RAM is an example of
primary memory. As soon as the computer is switched off the contents
of the primary memory is lost. The primary memory is much
faster in speed than the secondary memory. Secondary memory
such as floppy disks, magnetic disk, etc., is located external to the
computer. Primary memory is more expensive than secondary
memory. Because of this, the size of primary memory is less than
that of secondary memory. We will discuss about secondary memory
in later lesson.
COMPUTER ORGANISATION.pdf (Size: 160.84 KB / Downloads: 116)
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 organized and how various operations are performed
between different parts to complete a specific task. As you know
from the previous lesson the internal architecture of computer may
differ from system to system, but the basic organization remains the
same for all computer systems.
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.
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. The result is then sent back
to the storage unit.
Output: This is the process of producing results from the data
for getting useful information. The results could either be displayed
on the screen or may be printed for future reference. The
output unit therefore allows the results to be either stored inside
the computer for further processing or may give you the
results in human readable form.
Control: The process of input, output, processing and storage is
performed under the supervision of a unit called ‘Control Unit’.
It decides when to start receiving data, when to stop it, where to
store data, etc. It takes care of step-by-step processing of all
operations inside the computer.
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. These are 1) arithmetic logical unit, 2) control unit,
and 3) central processing unit.
(a) Arithmetic Logical Unit (ALU)
After you enter data through the input device it is stored in the
primary storage unit. Arithmetic Logical Unit performs the actual
processing of data and instruction. 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.
MEMORY SYSTEM IN A COMPUTER
There are two kinds of computer memory: primary and secondary.
Primary memory is an integral part of the computer system and is
accessible directly by the processing unit. RAM is an example of
primary memory. As soon as the computer is switched off the contents
of the primary memory is lost. The primary memory is much
faster in speed than the secondary memory. Secondary memory
such as floppy disks, magnetic disk, etc., is located external to the
computer. Primary memory is more expensive than secondary
memory. Because of this, the size of primary memory is less than
that of secondary memory. We will discuss about secondary memory
in later lesson.