The document is a learning module that teaches students about computer hardware components. It contains information on the system unit, motherboard, CPU, RAM, ROM, and expansion slots. The module includes activities to identify components of the system unit and motherboard. It provides descriptions of the main components and their functions, such as the CPU processes instructions, RAM is temporary memory, and ROM stores permanent programs.

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2. ICTL For Secondary School - Computer Hardware Module
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MODULE 3
SYSTEM UNIT
Curriculum Development Centre
Ministry of Education Malaysia

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1. Name of Module : System Unit
2. Learning Outcomes:The students should be able to:
• identify the components of a system unit
• state the functions of the main components of a system unit
• state the functions of cpu, ram, rom and expansions slots found
on the motherboard
3. Knowledge and Skills:
• main components in the computer system
4. Module Summary: At the end of the module, a student is able to :
• identify main components of system unit and motherboard
• state the functions of main components of system unit
• state the functions of CPU, RAM, ROM and expansion slot
This module contains 2 activities:
Activity 1 : Identify the components of a system unit
Activity 2 : Identify the components of a motherboard
As you are doing this module, use the computer in the lab to identify the components in the
system unit.

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Notes: What is system unit?
Box-like case that contains computer’s electronic components
Sometimes called the chassis
Figure 1 Examples of System Unit

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Activity 1 : Identify the components of a system unit
Inside view of system unit
Figure 2 Inside view of System Unit

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Front layer of a system unit
DVD-ROM drive
CD-ROM/CD-RW drive
Zip drive
Floppy disk drive
Empty drive bay
Power button
Reset button
Figure 3 Front View of a System Unit

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Input/Output port (I/O port)
keyboard
USB
USB
mouse
telephone
line in
game port
monitor
svideo out
network
cable TV
speaker
serial port
microphone
telephone
line out
FM reception
printer (parallel
port)
Power port
Figure 4 Back View of a System Unit

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Functions of the main components of a system unit
No. Components Functions
1. Input/Output port
(I/O port)
A port is the point at which a peripheral attaches to a system unit
so that the peripheral can send data to or receive information from
the computer.
An external device, such as a keyboard, monitor, printer, mouse
and microphone is often attached by a cable to a port on the
system unit.
The back of the system unit contains so many ports. Some newer
personal computers also have ports on the front of the system unit.
Ports have different types of connectors. A connector joins a cable
to a peripheral. One end of a cable attaches to the connector on
the system unit and the other end of the cable attaches to a
connector on the peripheral.
2. Power button To start on computer
3. Reset button Kick of soft boot, instructing the computer to go through the
process of shutting down, which would clear memory and reset
devices to their initialized state. It simply removes power
immediately.
4. Motherboard Main circuit board of the system unit, which has some electronic
components attached to it and others built into it.
5. Power Supply Convert standard electrical power into the form that computer can
use. If a power supply is not providing the necessary power, the
computer will not function properly.
6. DVD-ROM drive A device that reads DVD-ROM, also can read audio CDs, CD-
ROMSs, CD-Rs and CD-RWs.
7. CD-ROM drive A device that reads audio CDs, CD-ROMs, CD-Rs and CD-RWs.
8. DVD/CD-RW
drive
It is a combination drive that reads DVD and CD media, it also
writes to CD-RW media. This drive also allows watching a DVD or
burn a CD.
9. Zip drive A high-capacity disk drive that reads from and writes on a Zip disk.
10. Floppy drive A device that reads from and writes on a floppy disk
11. Hard disk drive Type of storage device that contains one or more inflexible, circular
platters that store data, instructions and information. Also called a
hard disk.

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Activity 2 : Identify the components of a motherboard
Expansion
slots
for RAM
Figure 5: Layout of a motherboard

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Expansion
Card
Expansion
Slots
CPU

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Functions of the components of the motherboard
No. Components Functions
1.
Central
Processing
Unit (CPU)
A Central Processing Unit or CPU is a microprocessor (or processor
for short). It is an integrated circuit chip that is capable of processing
electronic signals. The CPU is the most important element in a
computer system.
A CPU interprets instructions given by the software and carries out
those instructions by processing data and controlling the rest of the
computer’s components.
2.
Random
Access
Memory
(RAM)
RAM is installed inside computers. RAM is also known as a
working memory.
The data in RAM can be read (retrieved) or written (stored).
RAM is volatile which means the programs and data in RAM
are lost when the computer is powered off.
A computer uses RAM to hold temporary instructions and data
needed to complete tasks. This enables the computer's CPU
(Central Processing Unit) to access instructions and data
stored in the memory very quickly.
RAM stores data during and after processing.
3.
Read Only
Memory
(ROM)
ROM is another type of memory permanently stored inside the
computer.
ROM is non-volatile. It holds the programs and data when the
computer is powered off.
Programs in ROM have been pre-recorded. It can only be
stored by the manufacturer; once it is done, it cannot be
changed.
Many complex functions, such as start up operating
instructions, translators for high-level languages and operating
systems are placed in ROM memory.
All the contents in ROM can be accessed and read but cannot
be changed.
4.
Expansion
Slots
Expansion slots are the sockets where the circuit boards or the
adapter cards can be inserted into the motherboard. It is a place to fit
an expansion card containing the circuitry that provides some
specialised capability, such as video acceleration, sound or disk drive
control.

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Appendix 1

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Worksheet 1
Label the system unit below with the words given.
Expansion
Cards
Power Supply Zip Drive Hard Disk Drive Floppy Drive
RAM Mother Board CD/DVD Drive Expansion
Slots
CPU Chip

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Worksheet 2
Look at the diagram carefully and match them to the name of the ports in the table given using
numbers.
No
Label of the ports
1
Power port
USB port
VGA port (Monitor display)
Serial port (Modem)
PS2 port (Mouse)
Game port (Joystick)
Audio ports (speaker, headphone
and microphone)
Parallel port (printer port)
PS2 port (keyboard)

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Worksheet 3
Names the component parts of the motherboard.

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Worksheet 4
Mark T for True and F for False
1. The processor (CPU) interprets and carries out the basic instructions that
operate a computer.
2. Computers can use only one processor at a time.
3. ROM is the main circuit board of the system unit.
4. Expansion slot is a socket on the motherboard that can hold an adapter card.
5. RAM is non-volatile
6. The most important chip on the main circuit board is the microprocessor chip.
7. I/O port is the point at which a peripheral attaches to a system unit so that the
peripheral can send data to or receive information from the computer.
8. Reset button is to start on computer.
9. A device that reads from and writes on a floppy disk is called hard disk drives.
10. Power supply convert standard electrical power into the form that computer
can use.

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Worksheet 5
Fill in the blank with the correct name of components and functions.
No. Components Functions
1. Input/Output port
(I/O port)
2.
To start on computer
3.
Reset button
4.
Main circuit board of the system unit, which has some electronic
components attached to it and others built into it.
5.
Convert standard electrical power into the form that computer can
use.
6.
DVD-ROM drive
7.
CD-ROM drive
8.
This drive also allows watching a DVD or burn a CD.
9.
A high-capacity disk drive that reads from and writes on a Zip disk.
10.
Floppy drive
11.
Type of storage device that contains one or more inflexible, circular
platters that store data, instructions and information.

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Worksheet 6
Find the differences between primary storage RAM and ROM
RAM ROM

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Reference
Cashman, S. (2006) Discovering Computers 2006. USA : Thomson Course Technology.
Ibrahim Ahmad, Mohd Hafiz et al (2007) Information and Communication Technology (ICT)
Based on SPM Syllabus. Selangor: Venton Publishing (M) Sdn Bhd.
NCC Education (2002) Computer Studies, Computer Ace. Sri Lanka : Computer Pioneers.
IBasic Computing (2003) by TMEdu Tech (M) Sdn Bhd
http://www.wikipedia.org
http://images.search.yahoo.com
http://www.google.com.my
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