This document provides an overview of the key components of a computer system, including: - Hardware components like the central processing unit (CPU), memory, input devices, output devices, and secondary storage devices. - Software components like operating systems, application programs, and examples of common operating systems and applications. - It describes the functions of the CPU and other central components of a computer system in processing instructions and transferring data.

1. UNESCO ICTLIP Module 1. Lesson 4. 1

2. Midnimo Group
Deeqo C/qaadir Ibraahim
Ayaan C/qaadir Xasan
Ikraam C/qaadir Jimcaale
Faadumo Daahir C/Raxmaan
UNESCO ICTLIP Module 1. Lesson 4. 2

3. Outlines
What is computer?
Hardware
Software
Central Processor Unit (CPU)
UNESCO ICTLIP Module 1. Lesson 4. 3

4. What Is a Computer?
A computer is an electronic device, operating under
the control of instructions stored in its own memory
Page 6
Information Processing Cycle

5. The Components of a Computer
A computer contains many electric, electronic, and
mechanical components known as hardware
Pages 6 - 8

6. The Components of a Computer
Page 7
Figure 1-3

7. Storage DevicesStorage Devices
Hard DiskHard Disk
Flash DriveFlash Drive
CD-ROMCD-ROM
DVD-ROMDVD-ROM

8. Parts of a Computer Input DevicesParts of a Computer Input Devices
MouseMouse
KeyboardKeyboard
MicrophoneMicrophone
ScannerScanner
WebcamWebcam

9. Parts of a Computer OutputParts of a Computer Output
DevicesDevices
Monitor
Printer
Speaker/Headphone

10. Advantages and Disadvantages
of Using Computers
Advantages of
Using Computers
Disadvantages of
Using Computers
Pages 9 - 10

11. Categories of Computers
Page 19

12. Personal Computers
A personal computer can perform all of its input,
processing, output, and storage activities by itself
Two popular architectures are the PC and the Apple
Desktop computer
Page 19
Figures 1-15 - 1-16

13. Mobile Computers and Mobile
Devices
Pages 20 - 23

14. Mobile Computers and Mobile
Devices
Pages 20 - 22
Figures 1-17 – 1-20
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Link from left navigation,
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below Chapter 1

15. Mobile Computers and Mobile
Devices
Pages 22 - 23
Figures 1-21 – 1-23
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click Chapter 1, Click Web
Link from left navigation,
then click Digital Cameras
below Chapter 1

16. Mainframes
A mainframe is a
large, expensive,
powerful computer
that can handle
hundreds or
thousands of
connected users
simultaneously
Page 25
Figure 1-26

17. Super computers
A supercomputer is the fastest, most powerful
computer
Fastest supercomputers are capable of processing
more than one quadrillion instructions in a single
second
k
Page 25
Figure 1-27
 Medicine.
 Nuclear Energy
 Online Banking
 Weather Forecasting
 Medicine.
 Nuclear Energy
 Online Banking
 Weather Forecasting

18. Computer Applications in Society
,
Pages 34 - 36
Figures 1-36 – 1-39

19. Computer Applications in Society
Pages 36 - 38
Figures 1-40 – 1-43
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then click OnStar
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20. Welcome to Ayaan
She is Explaining Hardwar
20

21. HARDWARE
HARDWARE is the collection of
physical elements that constitute
a computer system.

23. Basic hardware of a PC
system
Central Processing Unit (CPU)
Memory Unit
Input Devices
Output Devices
Secondary Storage Devices

24. 1. Central Processing
Unit
Brain of the computer.
It directs and controls the entire computer
system and performs all arithmetic and logical
operations.

25. 2. Memory Unit
Where the programs and data
are stored .
READ ONLY MEMORY (ROM)
contains the pre-programmed
computer instructions such as
the Basic Input Output System
(BIOS).
RANDOM ACCESS MEMORY
(RAM) is used to store the
programs and data that you will
run. Exists only when there is
power.

26. 3. Input Devices
Allows data and programs to be sent to the
CPU.
Keyboard
Mouse
Joystick
Microphone
Webcam
Scanner
Monitor

27. THE KEYBOARD
The keyboard was one of the first peripherals to be
used with computers, and it is still the primary
input device for entering text and numbers. A
standard keyboard includes about 100 keys;
each key sends a different signal to the CPU.

28. Numeric keys Function keys
Space bar Arrow keys
ShiftkeyCapslockEscape
Control key
ENTER KEY
TAB KEY
ALT (Alternate) key
Backspace
ALPHABET KEYS
Shortcut key
Start key

29. Two Types of Mouse
Mechanical - a type of
computer mouse that has a
rubber or metal ball on its
underside and it can roll in
every direction.
Optical: This type uses a
laser for detecting the mouse's
movement.

30. Scanning Devices
Optical scanners
Card readers
Bar code readers
Character and mark recognition
devices

31. 4. Output Devices
Media used by the computer in
displaying its responses to our
requests and instructions.
Monitor
Audio Speakers
Printer

32. Types of Monitor
Cathode Ray Tube (CRT)
Liquid Crystal Display (LCD)

33. Printers
IMPACT PRINTERS uses pressure by physically
striking the paper. Ex. Daisy wheel printers, line
printers, dot matrix printers & band printers.
NON-IMPACT PRINTER does not apply
pressure on the paper but instead produces
character by using lasers, ink spray,
photography or heat.

34. Dot matrix
printer
Inkjet printerLaser
printer

35. 5. Secondary Storage
Devices
Attached to the computer system
to allow you to store programs and
data permanently for the purpose
of retrieving them for future use.
Floppy disk, Hard disk, CD Rom

36. Floppy Disk
The most common secondary
storage device
3.5” disk – 1.44MB

37. Hard Disk Drive or Hard
Disk
Made of rigid materials unlike floppy disks
Holds a greater amount of data
10MB in 1980s
600MB in mid 1990s
4.3GB in 1999
180GB in 2001
400GB - 2004

38. Optical Discs
A standard part of modern desktop
machines, especially used for
multimedia purposes and preferred
in loading applications.

39. Parts that Build Up A System
Unit
Casing or
cover
Power Supply
Motherboard
Microprocessor
Memory
Video Card
Sound card
Floppy disk
drive
Hard disk drive
CD-ROM drive
MODEM

40. Casing or cover
.
Protects the computer
circuits, cooling and
system organization.

41. Power Supply
Responsible for powering every device in your
computer.
Parts of a Power supply:
Disk drive connectors
Motherboard connector
Power supply fan
Power switch
Input voltage selector
Cover
Power plugs receptacle

42. Motherboard
The physical arrangement in a computer that
contains the computer’s basic circuitry and
components.
Components are:
Microprocessor
(Optional) Coprocessors
Memory
Basic Input/Output System (BIOS)
Expansion Slot
Interconnecting circuitry

44. Expansion Slots
Graphic cards
Sound cards
Modem cards
Network interface cards/network
adapter

45. Welcome to Ikraam
She is Explaining Softwar
UNESCO ICTLIP Module 1. Lesson 4. 45

46. SOFTWARE

Programs written in a special language with a
series of instructions to a computer or its
peripherals that cause the computer to solve a
problem or perform a task to achieve a
specific set of results.

Simply a set of instruction necessary for a
computer to accomplish required tasks.

47. UNESCO ICTLIP Module 1. Lesson 4. 47
Software
Software make up the set of
instructions for the computer. Without
software, the computer will not be able
to perform the tasks that you would
like it to do.

48. 
Operating System
controls all machine activities
provides the user interface to the computer
manages resources such as the CPU and memory
DOS, Windows XP, Unix, Linux, Mac OS

Application program
generic term for any other kind of software
(custom made)
MS Word, MS Excel, Games,….. Library
softwares e.g, Koha, WINISIS, LIMS, LAMP….
TYPES OF SOFTWARE

49. UNESCO ICTLIP Module 1. Lesson 4. 49
Operating system
An organized collection of system programs
which serve as the interface between the user
or application and the computer.
It manages the hardware resources:
CPU management to facilitate sharing
execution time of processes
Memory management to allocate memory
resources dynamically
I/O management to handle reading and
writing devices

50. UNESCO ICTLIP Module 1. Lesson 4.
Disk Operating Systems (DOS)
Disk Operating System (DOS) is a generic
term describing any operating system that
is loaded from disk devices when the
system is started or rebooted.
It is not a user friendly OS since users
need to memorize commands and issue it
by typing line by line. This known as
command line interface. Very few end
users use DOS nowadays.

51. UNESCO ICTLIP Module 1. Lesson 4. 51
Microsoft Windows
A graphical user interface (GUI) originally
running on DOS (Windows 3.x) that
allows multitasking or the ability to run
several programs at the same time.
Windows 95 / Windows NT that no longer
runs on DOS
About 75% of the world’s PCs use the
Windows operating system. The present
versions in use are Windows 98,
Windows Me and Windows 2000.

52. UNESCO ICTLIP Module 1. Lesson 4. 52
Other operating systems
IBM OS/2
Macintosh OS
SCO Unix
Linux
Other Proprietary OS

53. UNESCO ICTLIP Module 1. Lesson 4. 53
Applications software
A set of instructions designed to
perform a specific task such as word
processing, accounting, cataloguing,
library management, animation, etc.

54. UNESCO ICTLIP Module 1. Lesson 4. 54
Types of applications software
The nature of the software
depends on the application
General purpose office software
Business management software
Special discipline software
Other applications

55. UNESCO ICTLIP Module 1. Lesson 4. 55
General purpose office software
Word processing: Example, MS Word
Spreadsheets: Example, Excel
Database management systems:
Example, MS Access, Oracle
Presentation/Graphics: Example,
Power Point, Corel

56. Welcome to Faadumo
She is Explaining CPU
(Centeral Processing Unit)
UNESCO ICTLIP Module 1. Lesson 4. 56

57. 57
Processor

58. What is processing ?
The processor is the brain of the PC sometimes
called microprocessor or CPU (Central Processing
Unit)
Converts data into in formation
Control center
Set of electronic circuitry that executes stored
program instruction
The CPU performs the system's calculating and
processing
UNESCO ICTLIP Module 1. Lesson 4. 58

59. 59
Cont…..
The processor and the main memory devices are
the intelligence of the computer. Housed by the
system unit, the processor also known as the
CPU (central processing unit) interprets and
executes instructions while the main memory
serves as the computer's "work space". The
processing power of a computer largely depends
on the speed of the processor and size of its
main memory. Faster processor results to faster
execution of instructions.

60. UNESCO ICTLIP Module 1. Lesson 3 60
Processor

61. UNESCO ICTLIP Module 1. Lesson 3 61
Cont.
The processor is often the most expensive
single component in the system.
A central processing unit (CPU) is
the electronic circuitry within
a computer that carries out
the instructions of a computer program by
performing the basic arithmetic, logical,
control and input/output (I/O) operations
specified by the instructions.

62. 62
Cont…..
The form, design and implementation of CPUs
have changed over the course of their
history, but their fundamental operation
remains almost unchanged.

63. 63
cont….
Principal components of a CPU include the arithmetic
logic unit (ALU) that performs arithmetic and logic
operations, processor registers that
supply operands to the ALU and store the results of
ALU operations, and a control unit that fetches
instructions from memory and "executes" them by
directing the coordinated operations of the ALU,
registers and other components.

64. 64
Operation
The fundamental operation of most CPUs, regardless of the
physical form they take, is to execute a sequence of
stored instructions that is called a program.
The instructions to be executed are kept in some kind
of computer memory.
Nearly all CPUs follow the fetch, decode and execute steps
in their operation, which are collectively known as
the instruction cycle.
After the execution of an instruction, the entire process
repeats with the next instruction cycle normally fetching the
next-in-sequence instruction because of the incremented
value in the program counter.

65. 65
Fetch
The first step fetch involves retrieving
an instruction (which is represented by a number
or sequence of numbers) from program memory.
The instruction's location (address) in program
memory is determined by a program counter
(PC), which stores a number that identifies the
address of the next instruction to be fetched.
After an instruction is fetched, the PC is
incremented by the length of the instruction so
that it will contain the address of the next
instruction in the sequence.

66. Decode
The instruction that the CPU fetches from memory
determines what the CPU will do.
In the decode step, performed by the circuitry
known as the instruction decoder, the instruction is
converted into signals that control other parts of the
CPU.
The way in which the instruction is interpreted is
defined by the CPU's instruction set architecture
(ISA).

67. Execute
After the fetch and decode steps, the execute step
is performed.
Depending on the CPU architecture, this may
consist of a single action or a sequence of actions.
During each action, various parts of the CPU are
electrically connected so they can perform all or
part of the desired operation and then the action is
completed, typically in response to a clock pulse.
Very often the results are written to an internal CPU
register for quick access by subsequent
instructions.

68. Cont.
In other cases results may be written to slower, but
less expensive and higher capacity main memory.
For example, if an addition instruction is to be
executed, the arithmetic logic unit (ALU) inputs are
connected to a pair of operand sources (numbers to
be summed), the ALU is configured to perform an
addition operation so that the sum of its operand
inputs will appear at its output, and the ALU output
is connected to storage (e.g., a register or memory)
that will receive the sum.

69. UNESCO ICTLIP Module 1. Lesson 4. 69

70. 70
Control unit
Part of the hardware that is in-charge.
Directs the computer system to execute
stored program instructions.
Communicates with other parts of the
hardware.
The control unit of the CPU contains circuitry
that uses electrical signals to direct the entire
computer system to carry out stored program
instructions.

71. UNESCO ICTLIP Module 1. Lesson 3 71
Arithmetic logic unit
Performs arithmetic operations
Performs logical operations
The arithmetic logic unit (ALU) is a
digital circuit within the processor that
performs integer arithmetic and bitwise
logic operations.
Depending on the instruction being
executed, the operands may come
from internal or external memory, or
they may be constants generated by
the ALU itself.

72. UNESCO ICTLIP Module 1. Lesson 3 72
Cont…..
The result consists of both a data word,
which may be stored in a register or
memory, and status information that is
typically stored in a special, internal CPU
register reserved for this purpose.

73. 73
Arithmetic Operations

74. UNESCO ICTLIP Module 1. Lesson 3 74
Logical Operations

75. Thank you for you
listening
75