CIT 191 MODULE 1
MODULE 1 COMPUTER HARDWARE
UNIT 1 COMPUTER HARDWARE COMPONENTS (1)
1.0 Introduction
Your Personal Computer (PC) is really a collection of separate items
working together as a team-with you as the captain. Some of these
components are essential; others simply make working more pleasant
or efficient. Adding extra items expands the variety of tasks you
can accomplish with your machine.
2.0 Learning Outcomes
The Learning Outcomes of this unit are to:
i. Familiarize the student with the components of the computer.
ii. Enable the student to appreciate the importance of each of the
components to the overall smooth operations of the computer.
iii. Make students to be able to couple a system together
3.0 The System Unit
The system unit is the main unit of a PC. It is the Computer itself
while other units attached to it are regarded as peripherals. It could be
viewed as the master conductor orchestrating your PC’s operation. It
is made up of several components like the Motherboard, Processor,
Buses, memory, power supply unit, etc. This unit (system unit) has
been confused over the years by novices as the CPU. This is not
true. The CPU (Central Processing Unit) or simply processor is a
component within the system unit and it is not the only thing that
makes up the system unit. Hence, it will be wrong to equate the
system unit with the CPU.
3.1 Front of the System Unit
Light
Your system may display a variety of colored light on the front panel,
including power and turbo signals, and light to indicate if the Hard or
Floppy disk are being read or written to.
Key Lock
You can stop intruders tampering with your PC by using the Lock on
the front panel. Turning the key prevents the key board from working.
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CIT 191 COMPUTER LABORATORY I
Turbo Button
Some PCs offer a choice of speeds at which they can run. A turbo
switch is usually left so the computer runs at its fastest speed.
Reset Button
If your PC “freezes” and won’t respond to any command, try starting
it up again using the reset button. Pressing the reset button loses all the
work you have not saved in that session, so use it only as a last resort.
Power On/Off
All PCs have main power switch on the system unit. Sometimes this
control is placed on the outside back panel.
CD-ROM DISK DRIVE
A CD-ROM Drive or optical drive is the device used to read Compact Disc
Read-Only Memory. CD-ROM drives have speeds ranging from 1x to 72x,
meaning it reads the CD roughly 72 times faster than the 1x version. As you
would imagine, these drives are capable of playing audio CDs and reading
data CDs, including CD-R and CD-RW discs.
3.2 Back of the System Unit
Fan Housing
The electronic components in your PC generate a lot of heat. To
prevent overheating, a fan at the back of the unit removes hot air from
the system.
Power “in” and “out” Sockets
Cables plugged into these sockets carry power from the electrical
outlet to the system unit and from the system unit to the monitor.
USB Ports
A USB port is a standard cable connection interface for personal computers
and consumer electronics devices. USB stands for Universal Serial Bus, an
industry standard for short-distance digital data communications. USB ports
allow devices such as keyboard, mouse etc. to be connected to each other
with and transfer digital data over USB cables.
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3.3 Inside The System Unit
The brain behind everything that happens in your PC is contained
within the system unit. Inside the unit are the impressive electronics
that run programs, handle instructions, and determine the results.
Most of the more important items are described below:
Battery
A small battery powers a clock to keep track of the time when the PC is
turned off. It also maintains low electricity to certain RAM chips that
record which components are installed.
Disk Drive Controller Card
This card controls the PC’s disk drive motors and transfers data.
The serial and parallel ports at the back of the card link internal PC
components with external devices such as mouse and printer.
Display Adapter Card (Video Card)
All the information your computer will display is stored in its memory.
To be useful, you need to see the information. The display adapter
card is the link between the PC’s memory and the monitor.
Expansion Slots
These long narrow connectors allow you to plug in expansion cards
(also known as adapter cards), which offer extra options not available
on a basic PC.
ROM Chips
Read-only memory (ROM) chips have data written on them during
manufacturing that tells the CPU what to do when the PC is switched
on. The data is always there, even when you switch the PC off.
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RAM Chips
When a computer is switched on and running a program, RAM
(Random Access Memory) is used for purposes such as holding the
program and its data. But when the PC is switched off, anything held in
RAM is lost.
Empty RAM Chip Slots
These slots let you expand your computer’s memory by adding extra
RAM chips or modules. Some PC’s work even faster because they
come equipped with Cache Memory. Cache Memory consists of
expensive and very fast memory chips that store the data or instructions
that the CPU will look at next. Cache memory can speed up work on
your computer enormously.
Central Processing Unit (CPU)
Intel Processor
The Microprocessor, or Central Processing Unit (CPU), is the
computer’s most important single item. It does all the PC’s thinking
and runs the programs (series of instructions) that you request.
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CPU Support Chips
These chips help the CPU manage all the other parts of the computer.
Math Coprocessor Slot
A math coprocessor, present in some PCs, assists the CPU in its
number-crunching activities (if programs have been designed to use it).
CPU fan
Speaker
The speaker emits the computer’s sound output.
Power Supply Unit
All the components in a PC need electrical supply. Most need a 5-
volt supply although the floppy disk drive motors required 12 volts. If
the components were connected to normal household current, they
would blow up, so the power supply unit converts high voltage
electrical current to a low voltage.
Hard Disk Drive
The hard disk is your computer’s main permanent storage unit,
holding large amount of data and programs. Unlike data held in
RAM, the information on the hard disk is not affected when the PC
is turned off – it remains there unless you instruct the PC to
overwrite it or the hard disk is damaged.
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CIT 191 COMPUTER LABORATORY I
Hard drive (Hard disk)
Motherboard
All the electronic components in a PC are mounted on a piece of
fiberglass called the motherboard. Fiberglass cannot conduct
electricity, so each component is insulated from all the others. Thin
lines of metal on the surface of the fiberglass connect pins from one
component to another, forming the computer’s electrical circuits.
Intel CPU
The earliest PCs were equipped with a CPU from Intel Corporation
called the 8088. the next generation of PCs used CPU known by
the number “80286 and were called “PC/AT” computers.
Subsequently, PCs have been supplied with more and more
powerful CPUs – the 80386, the 80486, and the more recent and
impressive of all, the Intel Pentium (I, II, III, IV& M).
All these PC processors belong to a family called 80 x 86. In
general, you can run the same software on PCs containing different
CPUs within this family. From the outside, the chips look different
only in sizes and number of pin-put inside, an 80486 has over one
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CIT 191 MODULE 1
million components to the 3,500 that were in the first 8088. Because of
these differences, the latest Pentiums runs over ten times faster.
4.0 Tutor-Marked Assignment
a. Make a list of 5 components that could be found inside the
computer systems unit.
b. Describe the functions of each of them.
c. Differentiate between CPU and the Systems unit.
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CIT 191 COMPUTER LABORATORY I
5.0 References/Further Reading
Akinyokun, O.C, (1999). Principles and Practice of Computing
Technology. International Publishers Limited, Ibadan.
Balogun, V.F., Daramola, O.A., Obe, O.O., Ojokoh, B.A., and
Oluwadare S.A., (2006). Introduction to Computing: A Practical
Approach. Tom-Ray Publications, Akure Richard H. Austing
and Lillian Cassel (1986). Computers in Focus. Books/Cole
Publication Company. Monterey, California.
Larry Long (1984). Introduction to Computers and Information
Processing. Prentice-Hall Inc., New Jersey.
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CIT 191 MODULE 1
UNIT 2 HARDWARE COMPONENT (2) – PERIPHERAL
DEVICES
1.0 Introduction
The computer peripheral devices are those devices which are attached to
the system unit. The devices are necessary to ensure that the computer
is able to accept input and display the result for the user. This section
therefore discusses the input unit and the output unit.
2.0 Learning Outcomes
The learning outcomes of this unit are to:
i. Expose the students to those components that make up the input
unit and the output unit.
ii. Enable students get deeper understanding of the functions of the
input and the output unit.
iii. Guide the students on the type of input unit and output unit
suitable for a particular computing environment.
3.0 Input Devices
3.1 Computer Keyboard
A Computer keyboard is identical to the conventional typewriter
keyboard. However, it has more keys than the typewriter keyboard. A
computer keyboard can be a dummy type or intelligent type. A
computer keyboard is considered to be intelligent if, in addition to
performing the routine functions characteristic of a typewriter
keyboard, it can initiate a series of actions for a computer to carry out
by mere pressing a key or combination of two or more keys. An
intelligent computer keyboard has a set of keys and when one of them is
pressed, the computer can be made to carry out a specific function. For
example, the pressing of a key may cause the computer to display a
menu list from which a human being may be prompted to select one.
The intelligent computer keyboard has four major divisions, namely:
Function keys, Alphanumeric keys, Numeric keys and Control keys.
In addition to the four types of keys, there are some special or important
keys such as the following:
(a) Return or Enter key
(b) Escape key denoted by ESC
(c) Control key denoted by CTRL
(d) Alternate key denoted by ALT
(e) Delete key denoted by DEL
(f) Insert key denoted by INS
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(g) Backspace key
(h) Shift key.
3.2 Mouse
A mouse looks like the electrical clipper in a barbing saloon. It
consists of a pointing device very sensitive to movements. It has a
roller ball and two or more buttons which can be pressed to make
selection. By moving the mouse on a flat smooth surface and clicking
one or combination of two buttons on its upper surface, a computer to
which it is connected can be sensitized and commanded to carry out
some specific tasks.
A mouse can be used to draw diagrams on computer screen more
effectively and efficiently than the computer keyboard. Generally, the
keyboard and the mouse do complement each other. For example, the
mouse can be used to highlight an item in a menu list while the
keyboard Enter Key can be pressed to activate or evoke the command
associated with the highlighted item.
A mouse is the primary input device for modern computers that
feature operating systems with a graphical user interface, such as
Windows 98 or Windows XP. While keyboards obviously excel at
entering text, numbers, and symbols, your mouse is the tool you'll use to
tell your computer what to do with all the data you've entered.
3.3 Output Device
3.3.1 Printers
A printer is the computer component that lets you create copies of the
information stored in your computer on paper. The printed material is
often called hard copy, to differentiate it from the data stored on a disk,
or held in the computer's memory.
3.3.2 Monitors
The monitor does not do any processing itself. The monitor only
displays the information that the video card tells it to. The two most
common monitor sizes are 15-inch and 17-inch. If you have an older,
hand- me-down PC or a very inexpensive starter PC, you may have a
smaller 14-inch monitor. 21-inch monitors are also available but mostly
used by graphics professionals.
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CIT 191 MODULE 1
3.3.3 Scanners
Scanners are peripheral devices used to digitize (convert to electronic
format) artwork, photographs, text, or other items from hard copy. In a
sense, a scanner works as a pair of eyes for your PC. Your eyes see an
image and translate the image into electrical impulses that travel to and
are interpreted by your brain. Similarly, a scanner captures images and
converts them to digital data that travel to and are interpreted by the
computer. A scanner works by dividing an image into microscopic
rows and columns and measuring, like the film in a camera, how
much light (or lack thereof) reflects from each individual intersection
of the rows and columns. Each reflection is recorded as a dot, or
picture element (pixel). After the scanner collects information from
each dot, it compiles the result into a digital file on the computer. There
are a wide variety of scanners that work in a number of different ways,
but the technology behind them is essentially the same. The following
sections discuss more popular types of scanners available today.
3.3.4 Speakers and Sound
The built-in speakers in most PC cases are used just for making system
sounds, such as warning beeps and action indicators. To play more
sophisticated sounds on your PC, you need a set of external speakers.
Usually speakers come in pairs, and there is a plug that connects them
to your sound card. Arrange the speakers with one on the left and one
on the right of your desk or work area to get a stereo effect.
Optionally, some speakers come with a subwoofer. This improves the
bass (low notes) sound. If you have a subwoofer with your speakers, it
should go on the floor under your desk.
4.0 Conclusion
The system unit cannot function without the peripheral devices. The
input and the output units are very important peripheral devices that
must be taken care of in setting up a computer system.
5.0 Summary
In this unit we have learnt the following:
i. Input unit which comprises
(a) T he keyboard – the different categories of keys on the keyboard
and their functions.
(b) The scanner – different types of scanners
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CIT 191 COMPUTER LABORATORY I
ii. The output unit which is made up of the
(a) Monitor,
(b) The printer and, (c) the speakers.
6.0 Tutor-Marked Assignment
a. Justify the need for the input and the output units in a computer
system.
b. Describe the functions of the following keys: the numeric keys,
control keys, shift keys and the function keys.
c. In what situation will you recommend the laserjet printer and
the dot matrix printer.
7.0 References/Further Reading
Akinyokun, O.C, (1999). Principles and Practice of Computing
Technology. International Publishers Limited, Ibadan
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CIT 191 MODULE 1
UNIT 3 AUXILLARY EQUIPMENT
1.0 Introduction
The auxiliary equipment as their name suggests are not computers but
are necessary in a computing environment in order to ensure proper
functioning and smooth running of computing activities. In this unit,
we shall address in some details the importance of equipment such as
air conditioner, voltage stabilizer, uninterruptible power system and
line transformer in a data processing environment.
2.0 Learning Outcomes
The Learning Outcomes of this unit are to:
i. Identify the auxiliary equipment in a computing environment.
ii. Discuss the importance of the auxiliary equipment to the smooth
running of a computing centre.
3.1 Air Conditioner
A Computer is an electronic machine. It is, therefore, capable of
generating heat. A computer is manufactured to operate in an
environment with a specific temperature range. When the
temperature of the environment in which a computer is kept falls
outside the specific range, the computer may function badly and
consequently get damaged.
The free air is basically, dust laden. Dust is metallic in nature and, as
such, capable of conducting electricity. If dust is allowed to settle
on a computer, particularly the electronic circuits, the dust can
bridge two circuits. The bridging of two electronic circuits may
cause a serious damage to the computer. Thus, air conditioners are
needed in a computer environment to:
(a.) Control the temperature
(b.) Prevent dust.
3.2 Voltage Stabilizer
A computer when switched on, takes off at a cold state, warms up and
gradually gets to a hot state. At a hot state, a computer is always
roaming in an attempt to find something to do. In a situation where the
public electricity such as that of PHCN in Nigeria is cut suddenly, the
computer would suddenly be brought to a halt. The sudden power cut
may cause the computer to lose the memory of some basic
housekeeping operations when power eventually returns and the
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CIT 191 COMPUTER LABORATORY I
computer is switched on. The sudden power cut may also cause
irreparable damages to the file the computer was processing at the time
the power was suddenly cut.
3.3 Line Voltage Transformer
We note that computers are built to operate within a specific range of
voltages. In the United State of America, computers are built to
operate on 110V. A voltage transformer is a device meant to step up or
step down a voltage as the case may be. In Nigeria, for example, a
110V computer requires a voltage transformer to step down the
240V to 110V. Similarly, in USA, a 240V current is connected
directly to a 110V computer, the computer power unit will blow up
almost immediately.
Today, the technology has improved tremendously such that if a
240V current is connected directly to a 110V computer, only a fuse,
rather than the power unit will blow up. It is worth mentioning, too,
that there is an advanced technology today which permits a computer to
operate effectively and efficiently with the power line voltage ranging
between 110V and 240V. The technology supports an inbuilt switch
which can be operated at two terminals namely: the 110V terminus
and 240V terminus. In recent times, the technology has been
improved upon such that computers are manufactured in such a way
that they can sense the voltage that is adequate. Thus, if one connects a
110V computer to a 240V current, the 110V computer has an in-built
line transformer which automatically steps down the 240V current to
110V.
3.4 Uninterruptible Power Supply System (UPS)
An Un-interruptible Power System (UPS) is an auxiliary hardware that
is capable of:
(a) Converting the public electricity raw line into fine line, that is,
conditioning the voltage that is fed into the computer.
(b) Storing electrical energy when the public electricity line is life
(c) Releasing the stored electrical energy to the computer
when the public electricity line is dead.
4.0 Conclusion
The computer is an expensive resource and as such requires adequate
protection from electrical damage. Similarly, the UPS is an expensive
resource; hence there is the need for it to be protected from electrical
damage, too. Therefore, in practice, it is desirable that the UPS be
protected by a voltage stabilizer which is rugged and less expensive.
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CIT 191 MODULE 1
The configuration presented in Figure is an example of a computer
environment characterized by the multiple levels of protection
from electrical damage. This arrangement is desirable in a situation
of electrical surge and blown out.
5.0 Summary
In this unit you have learnt the following:
i. Auxiliary devices create a facilitative and conducive
environment for smooth operation of computers and the user.
ii. Voltage stabilizers help to protect computing equipment from
damage due to power surge.
iii. UPS protects the computing equipment and the software from
power outage during computing session. The UPS with the help
of its internal battery stores electrical energy while power is on
and releases power stored to the computer whenever power is
off. This enables the user to end the working session and shut
down normally.
iv. A voltage transformer is a device meant to step up or step down
a voltage as the case may be.
6.0 Tutor-Marked Assignment
With the aid of annotated diagram, describe the arrangement of the
following auxiliary equipment: UPS, line voltage transformer and
voltage stabilizer in relation to PHCN power source and the
computer.
7.0 References/Further Reading
Akinyokun, O.C, (1999). Principles and Practice of Computing
Technology. International Publishers Limited, Ibadan.
Balogun, V.F., Daramola, O.A., Obe, O.O., Ojokoh, B.A., and
Oluwadare S.A., (2006). Introduction to Computing: A Practical
Approach. Tom-Ray Publications, Akure.
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