Lecture2.pptx

BASIC COMPUTER
ORGANIZATION
Ishrat Nahar Farhana
Lecturer
Department of CSIT
Southern University Bangladesh
Lecture 2:

Learning Objectives
 Basic Operations of a Computer System
 Basic Organization of a Computer System
 Input, output and Storage Unit
 Arithmetic Logic Unit (ALU)
 Control Unit (CU)
 Central Processing Unit (CPU)
 Computer as a system

The Five Basic Operations of a
Computer System
 Inputting
The process of entering data and instructions into the computer
system
 Storing
Saving data and instructions to make them readily available
for initial or additional processing whenever required
 Processing
Performing arithmetic operations (add, subtract, multiply, divide,
etc.) or logical operations (comparisons like equal to, less than,
greater than, etc.) on data to convert them into useful information

The Five Basic Operations of a
Computer System
o Outputting
The process of producing useful information or
results for the user such as a printed report or visual
display
o Controlling
Directing the manner and sequence in which all of
the above operations are performed

Basic Organization of a Computer System
Storage Unit
Central Processing Unit (CPU)

Input Unit
An input unit of a computer system performs the following
functions:
 It accepts (or reads) instructions and data from outside world
 It converts these instructions and data in computer acceptable
form
 It supplies the converted instructions and data to the computer
system for further processing

Output Unit
An output unit of a computer system performs the
following functions
 It accepts the results produced by the computer, which are in
coded form and hence, cannot be easily understood by us
 It converts these coded results to human acceptable (readable)
form
 It supplies the converted results to outside world

Storage Unit
The storage unit of a computer system holds (or stores)
the following
 Data and instructions required for processing (received from input
devices)
 Intermediate results of processing
 Final results of processing, before they are released to an output
device

Two Types of Storage
1) Primary storage
 Used to hold running program instructions
 Used to hold data, intermediate results, and
 results of ongoing processing of job(s)
 Fast in operation
 Small Capacity
 Expensive
 Volatile (looses data on power dissipation)

Two Types of Storage
2) Secondary storage
 Used to hold stored program instructions
 Used to hold data and information of stored jobs
 Slower than primary storage
 Large Capacity
 Lot cheaper that primary storage
 Retains data even without power

Arithmetic Logic Unit (ALU)
Arithmetic Logic Unit of a computer system is the place where the
actual executions of instructions takes place during processing
operation
This unit consists of two subsections namely,
 Arithmetic Section
 Logic Section
 Arithmetic Section
Function of arithmetic section is to perform arithmetic operations like
addition, subtraction, multiplication, and division. All complex operations
are done by making repetitive use of the above operations.
 Logic Section
Function of logic section is to perform logic operations such as
comparing, selecting, matching, and merging of data.

Control Unit (CU)
 Control Unit of a computer system manages and coordinates the
operations of all other components of the computer system
 This unit controls the operations of all parts of the computer but
does not carry out any actual data processing operations
Functions of this unit are −
 It is responsible for controlling the transfer of data and instructions
among other units of a computer.
 It manages and coordinates all the units of the computer.
 It obtains the instructions from the memory, interprets them, and directs
the operation of the computer.
 It communicates with Input / Output devices for transfer of data or
results from storage.
 It does not process or store data.

Central Processing Unit (CPU)
Central Processing Unit (CPU) consists of the following
features −
 CPU is considered as the brain of the computer.
 CPU performs all types of data processing operations.
 It stores data, intermediate results, and instructions (program).
 It controls the operation of all parts of the computer.

The System Concept
A system has following three characteristics:
 A system has more than one element
 All elements of a system are logically related
 All elements of a system are controlled in a manner to achieve
the system goal
A computer is a system as it comprises of integrated
components (input unit, output unit, storage unit, and CPU)
that work together to perform the steps called for in the
executing program

Lecture2.pptx

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