Understanding Computer System

1. Computer System
Presented By:
Pratibha Sagar
MJP Rohilkhand University,
Bareilly

2. A Computer is a
programmable
electronic machine
that performs high-
speed mathematical
or logical operations,
stores & processes
data to get meaningful
information.
Definition of Computer

3. 1. Computer
Hardware
2. Computer
Software
Computer Parts

4. Computer
Hardware is
the physical
part of the
computer
system, the
machinery and
equipment.
Parts of the
computer “you
can see”
Computer Hardware

5. Computer Software
Computer Software are programs
that tell the computer what to do.

6. Computer System

7. System Unit - the metal box that houses
the processor, main memory, and
secondary storage devices.
– Abbreviated to “CPU”
Input and output devices - attached to
the system unit via a device controller.
– The terms "input" and "output" tell you if
data flow is into or out of the system unit.
– Abbreviated to “I/O”
Parts of a Computer System

8. Basic Operations of Computer
It accepts data or instructions by any
way of input.
It stores data.
It can process data as required by the
user.
It controls all operations inside a
computer.
It gives results in the form of output

9. The Components Inside

10. The Components Inside
The components inside the CPU are
– Mother board
– Bus
– Cards
– Ports
– Memory
– Hard Disk Drive
– Floppy Disk Drive
– Power Supply Unit
– Computer Clock (Real Time Clock)

11. Computer Inside

12. An Inside View

13. The components inside shows the
Bus - transports data between the
processor and other components
Motherboard - consists of a
complex group of circuits
Controllers - controls the
input/output work in the computer
The Components Inside

14. Cards - fixed on slots contained in
buses to enable the expansion of
the computer
Ports - entry and exit points of
buses
The Components Inside

15. An Inside View
Hard Drive Bus
Hard Disk Driver

16. Outer View of Computer
(Front)

17. Outer View of Computer
(Back)

18. Expansion Ports
Jacks or connectors
Mouse, keyboard,
serial, USB
Cables

19. Auxiliary (Secondary)
Memory
Input
devices
Output
devices
CPU- Central
Processing Unit
• Control Unit
•Arithmetic Logic
Unit (ALU)
Main/Primary
Memory (RAM/ROM)
How these Components Work
Together
Monitor,
Printer
Keyboard,
Mouse
Hard drive CD R/W, DVD, floppy drive,
ZIP drive, Flash memory
Bus
Bus

20. Computer Devices that input/provides
data to a computer from the outside
world
Examples
Key Board
Mouse
Scanner
Digital Camera
Computer Input Devices

21. Input Devices

22. Input Devices

23. The CPU
The CPU is Central Processing Unit
i.e. “Heart” of Computer System.
It is a silicon chip that contains
millions of tiny electrical
components.
The CPU’s three main parts are:
– Control Unit
– Arithmetic Logic Unit (ALU)
– Registers

24. Arithmetic / Logic Unit
Registers
Control Unit
Small, fast
storage areas for
instructions and
data
Performs calculations
and decisions
Coordinates
processing steps
The CPU

25. The CPU controls all of the other resources within the
system, in order to accomplish a task.
Component Interaction

26. Any type of device that provides
data from a computer to the
outside world
Examples of output data:
– A printed report
– An image such as a picture
– A sound
Common output devices include:
– Monitor (display screen)
– Printer
Output Devices

27. Output Devices

28. User hits
the ‘2’ key then
Enter
Output 4 on
the screen
ALU adds
2 + The
user
input
Y = 4
Main Memory
Program:
INPUT X
Y = X+2
OUTPUT Y
The performance of the CPU is dependent on both its speed and
memory
Working of the CPU

29. Access to Instructions
The hard disk is too slow to provide instructions to
the CPU. So programs are first loaded into main
memory, which is much faster. The CPU can then
access the instructions more quickly.

30. Cache Memory
But as CPU speeds became faster,
the main memory couldn’t provide
the CPU with the instructions at a
fast enough rate.
So even faster memory ( cache
memory) is now placed between the
CPU and main memory to provide
the instructions at quicker rate to the
CPU.

31. Cache Memory
When an instruction or data is accessed from main
memory, it is placed in the cache. Second and
subsequent use of the same instruction/data will
then be faster, since it is accessed directly from the
cache.

32. User’s View of Computer System