ICT
TR. Pacutho Andrew ICT Department NGSS 1

Chapter 2: Computer Hardware and System Start up.
i.
ii.
Meaning of Computer Hardware
Assembling a Computer System
iii. Starting and Shutting down a Computer System
iv. Activity 2.4: Starting and shutting down a Computer
System

CHAPTER 2:
Computer Hardware and System Start up
By the end of this chapter you should be able to:
a) know the physical devices of a computer system and how each
operates.
b) assemble a computer system.
c) safely start and shut down a computer system.
d) use computer peripheral tools.
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Meaning of Computer Hardware
QTN: Have you ever used a desktop computer or a laptop
computer?
Is a computer one single part, or a group of parts?
Generally, a computer is a system of many parts working
together as shown in Figure 2.1. below
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• The tangible parts that you can touch and feel such as
the monitor, keyboard, mouse, disk drives, printer,
scanner and speakers, are collectively referred to as
hardware.
• The opposite of hardware is software, which refers to
the instructions or programs that tell the hardware what
to do. Software is intangible
Qtn: Define;
i. Hardware…………………………………………………
………………………………………………………………
…………........
ii. Software…………………………………………………
………………………………………………………………
…………………...
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Categories Of Computer Hardware
Hardware devices are categorized
according to their functions. The various
hardware categories include
i.
ii.
iii.
iv.
v.
Input devices
Output devices
Storage hardware
Processing hardware
Communication hardware
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INPUT HARDWARE
Input hardware refers to hardware that is
used to enter/ compose/ feed instructions
into the computer.
Categories of input hardware
i. Pointing input devices.
ii. Text input hardware devices.
iii. Gaming input hardware devices.
iv. Video, image input devices.
v. Audio input devices.
vi. Biometric input devices.
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POINTING DEVICES.
These are input devices that control the movement of
a cursor or pointer in a Graphical User Interface
(GUI). eg
•Mouse
•Tracker ball
•Touch screen
•Touch pad (glide pad)
•Pointing stick
•Stylus
•Graphics tablet
•Light pen
•Cyber glove
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THE MOUSEAND ITS PARTS
• .
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2. TRACKER BALL
.
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3. TOUCH SCREEN.
,
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4. Touch pad(glide pad)
.
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5. POINTING STICK.
,
14

6. STYLUS
.
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7. GRAPHICS TABLET
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8. LIGHT PEN.
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B. TEXT INPUT HARDWARE.
• Keyboard
• Bar code readers
• Magnetic Ink Character Reader (MICR reader)
• Quick Response Code Reader(QR Code reader)
• Optical character recognition devices
• Speech recognition systems
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1. KEYBOARD
It is a primary input device made up of numbers, letters,
symbols and special keys used to enter data into the
computer. The arrangement of keys on the keyboard is
called key board layout.
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2. Abar code reader, also called a bar code scanner, is an optical
reader that uses laser beams to read bar codes by using light
patterns that pass through the bar code lines.
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3. SPEECH RECOGNITION SYSTEMS
•These are systems that accept speech input
and act on it or transcribe it into written
language.
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5. QUICK RESPONSE CODE READER
(QR READER)
•The QR code is the trademark for a type
of two-dimensional bar codes in which
information is represented by black and
white dots (so-called "square data dots"
or "data pixels").
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GAMING INPUT HARDWARE DEVICE
These are devices with which one control and
play a game on personal computer.
•Joystick
•Game pad (or joy pad)
•Paddle
•Power Pad
•Light guns,
•Dance pads
•Motion-sensing controllers
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IMAGE, VIDEO INPUT HARDWAREDEVICES
Are devices that are used to record video,
images and other moving activities.
EXAMPLES
•Image scanner
•3D scanner
•Digital camera
•Digital camcorder
•Webcam
•Digital Video Recorder (DVR)
•Digital video cameras
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1. IMAGE SCANNER
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3. DIGITALCAMERA
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4. DIGITALCAMCORDER
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5. WEBCAM
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6. DIGITAL VIDEO CAMERAS
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AUDIO INPUT DEVICES
Are devices with that are used to capture
sound waves and convert it into a digital file on
a computer.
•Digital voice recorder.
•Microphone
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BIOMETRIC INPUT HARDWARE
This an input device used in the identification of a
person by the measurement of their biological
features/characteristics. eg
1. Finger print scanner
2. Face verification systems
3. Hand geometry system
4. Voice recognition system
5. An iris recognition system
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FINGER PRINT SCANNER
• Afingerprint scanner captures curves and indentations of a
fingerprint.
• Some supermarkets and shops now use fingerprint
readers as a means of payment, where the customer's
fingerprint is linked to a payment method such as a
account or credit card.
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FACE RECOGNITION SYSTEMS
•Aface recognition system
captures a live face image and
compares it with a stored image
to determine if the person is a
legitimate user.
•Some buildings use face
recognitionsystems to secure
access to rooms.
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AVOICE VERIFICATION SYSTEM compares a
person's live speech with their stored voice
pattern. Some larger organizations use voice
verification systems as time and attendance
devices.
ASIGNATURE VERIFICATION SYSTEM
recognizes the shape of your handwritten
signature, as well as measures the pressure
exerted and the motion used to write the
signature.
Signature verification system uses a specialized
pen and tablet.
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IRIS RECOGNITION SYSTEM
High security areas use iris recognition systems. The
camera in an iris recognition system uses iris
recognition technology to read patterns in the iris of
the eye. Iris recognition systems are used by
government security organizations, the military, and
financial institutions that deal with highly sensitive
data.
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Exercise
1(a). What is a biometric device?
……………………………………………………………
………………………………………………………
(b). How do biometrics devices work?
………………………………………………………..
(c). List any five biometric systems/devices
……………………………………………………………
……………………………………………………..
(d).Mention advantages of using biometric
devices today.
…………………………………………………………..
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OUTPUT HARDWARE
Output is data that has been processed into a
useful form called information.
Output device is any hardware capable of
conveying information to one or more people.
Eg printers; speakers, headsets and
earphones; fax machines and fax modems;
multifunction peripherals; data projectors;
interactive whiteboards; etc
CATEGORIES OF OUTPUT
•Text output
•Graphics
•Audio
•Video/image output
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DISPLAY DEVICES
Display devices are output devices that visually present text,
graphics, and video information. The information displayed on the
screen is called soft copy.
Examples of display devices include; Monitor, Projector,
interactive boards, screens.
Soft Copy is an electronic copy of some type of data, such as a
file viewed on a computer's display medium.
Desktop computers typically use a monitor as their display device.
Amonitor is a display device that is packaged as a separate
peripheral.
Monitors can be of flat-panel displays and CRT(Cathode Ray
Tube) monitors.
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Aflat-panel display is a lightweight display device
with a shallow depth and flat screen that typically
uses LCD (liquid crystal display) or gas plasma
technology.
Types of flat -panel displays include
i. LCD monitors
ii. Plasma monitors.
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An LCD Monitor
• .
APlasma Monitor
• ,
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CRT Monitors
ACRT monitor is a desktop monitor that contains a
cathode-ray tube. Acathode-ray tube (CRT) is a large,
sealed glass tube. The front of the tube is the screen.
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Advantages of CRT monitors over flat panel
monitors
1. CRT monitors have better color representation
/output than flat panel.
2. Can be viewed from a very wide angle.
3. Cheaper in cost than LCD monitors in general.
Advantages of flat panel monitors over CRT
monitors
1. LCD monitors consume less power than
CRT monitors.
2. LCD monitors are smaller and weigh less
space than traditional CRT monitors.
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3. Radiation emitted by LCD monitors is
less than that of CRTs.
4. They have a narrow viewing angle
compared to CRT monitors.
5. They have a higher refresh rate compared
to CRT monitors.
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PROJECTORS
•This displays information from the
computer screen on a large screen that
the audience can clearly see.
•Most schools use projectors in their
classrooms.
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PRINTERS
•Aprinter is an output device that
produces text and graphics on a
physical medium such as paper.
•Printed information is called hard
copy because the information exists
physically and is a more permanent
form of output than that presented
on a display device (soft copy).
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The material on which information is
printed is called a print medium. This
can be paper, cloth, glass, wood,
plastic, etc
Printers can be categorized in several
ways the most common distinction is
the IMPACT and NON-IMPACT
printers.
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IMPACT PRINTERS
These are printers that produce hard
copy output by the print heads
physically touching the print media.
Examples of such printers include;
1. Character printers
2. Line printers
3. Dot matrix printers
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Character printers: These print one
character at a time mimicking a typewriter.
E.g. daisy wheel printer
Line printers: These print an entire line at
a time.
Dot matrix printers: These form
characters by print heads forming a pattern
of dots on paper to give an out put.
Page printers: These print an entire page
at a time. They are faster than the above
categories
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GENERAL CHARACTERISTICS OF IMPACT PRINTERS
1.Produces text and images when tiny wire pins on print
head strike the ink ribbon by physically contacting the
print media
2.Low printing speed
3.Print quality is lower in some types
4.Produce near letter quality (NLQ) print only, which is
just suitable for printing mailing labels, envelopes, or
invoices
5.Uses ink ribbon
6.Less expensive
7.Reliable, durable (lasting for a long time)
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ADVANTAGES OF IMPACT PRINTERS
•They are easier to maintain since they
withstand most conditions.
•They are less expensive compared to
non-impact printers.
•They have a bigger long life spans.
•Can print heavy graphics.
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DISADVANTAGES OF USING IMPACT
PRINTERS
•They are noisy during operation.
•They tend to overheat during operation.
•They produce poor quality compared to
non-impact printers.
•Their printing speed is slower compared
to non-impact printers.
•They require special form of papers.
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NON-IMPACT
•These are printers that produce
hard copy output without the print
heads physically touching the print
media.
•Inkjet printers
•Photo printers
•Laserjet printer
•Thermal printers
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a) Inkjet printers
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b) Photo printers
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c) LaserJet printers
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d) Thermal printers
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ADVANTAGES OF USING NON- IMPACT
PRINTERS
•They are quiet during operation.
•They don’t overheat during
operation.
•They produce good quality outputs
compared to impact printers.
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•Their printing speed faster
compared to impact printers.
•They require little power
compared to the impact printers.
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DISADVANTAGES OF USING NON-
IMPACT PRINTERS
•They are more expensive compared
to impact printers.
•Most are selective on the type of
paper they use.
•Cartridges are special for most of
these computers.
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FACTORS TO CONSIDER WHILE
OBTAININGAPRINTER FOR USE
• Aprinter’s resolution helps to determine quality of images it can
produce.
• Aprinter’s speed determines how quickly it can output pages.
• Amount of memory available in the printer for buffering and spooling
activities.
• Cost of the printer.
• Type of printer to be bought? Is it impact or non impact?
• Running cost of the printer.
• Capability of sharing the printer through a network for large
organisations.
• Ink Cartridges and Toner.
• Purpose of the printer.
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HOW TO CARE FOR PRINTERS
• Keep your printer clean – Be sure to clean the printer regularly
inside-out and close the paper feed trays when not in use.
• Keep it covered - When not in use, cover the whole printer unit
with a cloth or a plastic cover.
• Turn it off - When the printer is not in use, press the Power
button on the printer to shut it down and turn off the mains.
• Use it frequently - Use your printer at least once every two
weeks to ensure that it is in a proper working condition.
• Always use original cartridges as recommended by the
manufacturer. Avoid cheap/refilled ink cartridges and toners
because they affect the printer’s performance and the quality of
your prints.
• Avoid low quality papers -Using cheap, low quality papers
with your printer can affect the print quality and cause paper
jams. Manufacturers generally specify the type of paper you
need to use.
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SPEAKERS (audio/speech)
•Audio output devices produce sound
/speech or beeps. These include;
Speakers.
Headphones/headsets.
Earphones.
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INPUT/OUTPUT DEVICES
There are devices that enter data into the
computer as well as present/display
information from the computer.
•Fax machine.
•Touch screen.
•Digital camera.
•Interactive white board (smart board).
•Multifunctional peripheral like printers,
scanners, etc
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TERMS:
Reading is the process of transferring data,
instructions, and information from a storage medium
into memory.
Writing is the process of transferring these items
from memory to a storage medium.
Memory is a temporary area for holding data,
instructions, and information.
Storage capacity refers to how much data a storage
medium is able to hold.
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Access time Refers to the time it takes to
locate an item on a storage medium.
Storage medium refers to the physical
material on which a computer keeps data.
Storage device refers to hardware
components that are used to record and
retrieve data to and from a storage medium
Transfer rate This refers to the speed at
which data is transferred from one device to
another.
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Data/information access mode
Refers to how an item can be accessed on a
medium either sequentially or randomly.
There are two type of data access modes i.e
•Direct/random access mode
This is a mode of access in which data
items are accessed without following any
sequence.
•Sequential access mode
This is a type access in which data items
are accessed in order from the first to the
last.
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FACTORS CONSIDERED IN CLASSIFYING STORAGE
•
•
•
•
•
Amount of data stored.
Method of data access.
Technology used to store data.
Whether the medium is fixed or removable
Whether the storage medium is internal or
external
• Whether the storage medium can hold data
for a short time or for a long period of time?
• Whether storage medium is fast or slow to
access
• Whether the storage capacity of medium can
be TR. David Bujaasi
chapter 2expanded or not.Ssalongo@ICT Dept-STSSN 68

TYPES OF MEMORY
PRIMARY MEMORY
The computer storage location that is directly accessed by
the computer’s CPU. For example RAM,ROM,CMOS,
Virtual Memory,Cache Memory
SECONDARY MEMORY
The computer storage not directly accessed by the
computer’s CPU.Also called removable storage.
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1.RANDOMACCESS MEMORY (RAM)
Is an example of primary volatile memory in
the system unit.Volatile memory looses its
content when the computer is turned off.
Contents in RAM can be updated,adjusted and
modified.
The two basic types of RAM are;
• Dynamic RAM
• Static RAM.
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2. READ ONLY MEMORY (ROM)
Is an example of non-volatile memory. ROM chips
contains data, instructions, or information, which
is recorded permanently by the manufacturers
are known as firmware.
Types of ROM
•PROM - Programmable read-only memory
•EPROM - Erasable programmable read-only memory
•EEPROM - Electrically Erasable Programmable
Read-Only Memory.
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RAM(randomaccessmemory) ROM(readonlymemory)
1.itisvolatile
2.itisreadandwrite
3.itcanbeincreasedor
changedoraltered
itisnon-volatile
itisreadonly
itisnormallynotincreased
orchangedoraltered
Differences between RAM & ROM
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3. VIRTUAL MEMORY
•Refers to memory (VM), borrowed from the
hard disk by the operating system to function
as additional RAM.
4. CACHE MEMORY
•This is a memory that stores frequently used
instructions and data in order to speed up the
processes of computing
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5. CMOS - COMPLEMENTARYMETAL-OXIDE
SEMICONDUCTOR
Is used to store configuration information about the
computer, which includes amount of memory,
types of disk drives, keyboard, monitor, current
date and time, etc.
CMOS chips use CMOS battery power to retain
information even when the computer is turned off.
The CMOS chip is updated whenever new
components are installed.
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7. BUFFER:
The temporary storage location mainly found in
output devices such as a printer.
8. CLIPBOARD
The temporary storage location mainly found in
input devices such as a keyboard and mouse.
During copy and paste, the copied work stays in the
clipboard until replaced by the newly copied work or
when the computer is switched off.
9. REGISTER: The temporary high speed storage
location in the CPU.
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FUNCTIONS OF PRIMARY MEMORY
•It holds programs and files under current use.
•Stores files needed for a complete boot process
of the computer.
•It determines efficiency and performance of a
computer.
•It provides extra space for the CPU while
processing data by swapping files in and out of
the hard drive.
•Primary memory enables the user to recover
work in memory for the last 5 minutes in case of
a power cut.
•Very important for a user to take a purchase
decision of a computer set
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MEMORY MEASUREMENT
•In a computer system, data is
represented using the binary coding
system
•Acombination of binary digits called
bits
•There are only two binary digits; 1(on)
and 0 (off). 8 of these bits are
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arranged to representDept-STSSNcharacter.77

MEMORY MEASUREMENT UNITS
Bit: This is the smallest unit of memory
measurement
Nibble: This is a group of four binary bits.
Byte: This is a set of eight bits. Each byte
represents a character.
Kilobyte (KBs): This is a set of 1024 bytes.
Megabyte(MBs): This is a set of 1024 KBs.
Gigabyte(GBs): This is a set of 1024 MBs.
Terabyte(TBs): This is a set of 1024 GBs
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SECONDARYSTORAGE
Secondary storage.
•This is also known as auxiliary storage which is
designed to retain data and instructions and
programs in a relatively permanent form.
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5.3.1 Categories of Secondary Storage Media
•There is a wide variety of storage devices in the
following categories.
•(A) Magnetic media,
•(B) Optical media
•(C) Solid-state media and
Other Types of Storage Media such as
• Photographic film
• Microfilm and Microfiche
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(A) Magnetic media
• Magnetic storage media represent data as magnetic
spots on the tape or disk, with a magnetized spot
representing a 1 bit and the absence of such a spot
representing a 0 bit.
• Common examples of magnetic media include:
•Magnetic tape
•Floppy disk,
•Hard disks
•Magnetic stripe Card
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(i) Magnetic tape
• ,
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(ii) Floppy disk (diskette)
.
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(iii) Hard disks
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iv. Magnetic stripe card
,
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(B) Optical Media
•An optical disc is a flat, round, portable
storage medium made of metal, plastic, and
lacquer that is written and read by a beam of
laser light.
•The reflected light is converted into a series of
bits that the computer can process.
•Optical discs used in personal computers are
4.75 inches in diameter. Smaller computers and
devices use mini discs that have a diameter of 3
inches or less.
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Care for Optical Discs
•Care for Optical Disks
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Categories of Optical Discs
• Two general categories are CDs and DVDs, with DVDs having
a much greater storage capacity than CDs.
• Examples of Optical Disks include:
• CD-ROM (compact disc read-only memory): These are written
by the manufacturer and can not be modified.Atypical CD-
ROM can hold from 650 MB to 1GB of data, but most hold
700MB.
• CD-R (compact disc-recordable) is a technology that allows
you to write on a compact disc using your own computer’s CD-
R drive.
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Categories of Optical Discs
• ACD-RW (compact disc-rewritable) is an erasable multisession
disc that you can write on multiple times.
• DVD-ROM (digital video disc-ROM).ADVD-ROM is an
extremely high capacity compact disc capable of storing from
4.7 GB to 17GB.
• DVDs are also available in a variety of recordable and rewritable
versions and formats such as DVD-R and DVD+R DVD+RW,
DVD+RE, and DVD+RAM.
• ABlu-ray Dics-ROM (BD-ROM) has storage capacities of up to
100 GB.
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BLUE RAY
• Refers to the blue laser used to read the disc, which
allows information to be stored at a greater density than
is possible with the longer-wavelength red laser used for
DVDs.
• These store large amounts of data than other optical
devices (up to 128GB)
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ADVANTAGES OF USINGACD – ROMS
• Much faster to access than a floppy but currently slower
than a hard disk .
• Can hold 650 MB -700 MB of data and more.
• Useful for the distribution of today’s large programs and
information libraries, which you can then copy (all or in part)
onto your hard disk.
• Also widely used by music industry as they give quality
sound and do not wear out like cassette tape.
• It is the safest form of storage, provided that you don’t
attack it with a sharp or heavy object.
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(C) Solid-state media
•Solid-state storage (SSS) is a type of computer
storage media that stores data electronically and
has no moving parts.
•Solid state is a non-volatile storage that employs
integrated circuits rather than mechanical,
magnetic or optical technology.
Examples include:
•Flash Memory Cards
•USB Flash Disks
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Flash memory cards
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USB flash disk
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CLOUD/ONLINE STORAGE
•Online / cloud storage
is storage for keeping
data with a third party
accessed via the
internet..
•Online storage is virtual
storage approach & its
accessed remotely
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CLASSES OF STORAGE BASED ON TECHNOLOGY
1. Magnetic Storage Technology is storage the uses magnetism to
keep data. Media in this class are; Magnetic tape, DigitalAudio
Tape, Floppy disk, Hard disk, Reel-to-reel audio tape recording,
Compact audio cassette
2. Optical Storage Technology is storage where data is written/ read
by use of laser. Media in the class are;Compact disc, DVD,
Blue ray
3. Solid State Storage Technology is storage that read/ writes data
on media without any moving parts. E.g.Flash disk, Memory
cards.
4. Online Storage Technology is storage over a network like the
internet e.g. Google drive, drop box, I-cloud, e-mail storage
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FUNCTIONS OF COMPUTER STORAGE MEDIA
• To serve & work as backing storage.
• To store large programs and files needed by the computer
to work.
• To keep user’s files for future use in a more permanent
nature.
• To act as a yardstick considered when a user is to take an
accurate decision before computer purchase.
• To work as an ideal storage location and distribution of
software products to end users
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FACTORS TO CONSIDER BEFORE BUYINGA NEW STORAGE
MEDIUM
• Capacity of the storage medium
• Whether removable or fixed
• The access speed of the storage medium
• The access method of storage medium
• Technology of the storage medium
• Access time of the storage medium
• The cost of the storage medium against the buyer’s
budget
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HOW TO CARE FOR STORAGE MEDIA
• Don’t eat anything while you are working and using storage
media.
• Install strong, genuine and updatedAnti-virus software to protect
storage media from malware.
• Keep away magnets from the magnetic storage media.
• Don’t keep your computer storage media in the moist
temperature..
• Don’t keep heavy or huge things on the storage media
• Keep away eatables or drinks of any type.
• Make your computer protected from the dust.
• Don’t keep storage media under direct sun light especially
optical storage media.
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CHAPTER QTNS
1.(a) Distinguish between softcopy and hardcopy output (02 marks)
(b) Give three situations where a hardcopy is preferred compared to a
soft copy (03 marks)
2.(a) What is meant by computer hardware? (01 mark)
(b) State four major classification of computer hardware (04 marks)
3.(a) Define the term input device? (01 mark)
(b) State four ways of inputting data into the computer, giving an
example for each (04 marks)
4.(a) Differentiate RAM from ROM (02 marks)
(b) List down any three factors that should be considered when
purchasing a computer (03 marks)
5.(a) state three devices that can be used as both input and output (03
marks)
(b) Mention any two practical uses of Light Emitting Diode(LED) on a
printer (02 marks)
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6 (a)Peter went to buy a monitor to use on his computer. He
preferred LCD monitors to CRT monitors. State three advantages of
LCDs over CRTs (03 marks)
(b) Mention two disadvantages of LCD technology as compared to
CRT (02 marks)
7(a) Define the following terms as used in display devices (03
marks)
i) Resolution
ii) Refresh rate
iii) Video card
(b) Outline any two factors to consider when choosing a monitor
(02 marks)
8(a) state the difference between impact and non-impact printers
(02 marks)
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9(a) Define the term multimedia as used in computing (02 marks)
(b) List three requirements of multimedia systems (03 marks)
10(a) what is meant by “dead tree edition” as used in computer
hardware (01 mark)
(b) State one specialized application of each of these Hardware
devices (04 marks)
i. Light pen
ii. Stylus and graphic tablet
iii. Barcode reader
iv.Optical Character Recognition (OCR) Reader
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11.Define the following terms as applied to computer hardware (05 marks)
i. cache memory
ii.serial port
iii.peripheral device
iv.primary memory
v.secondary memory
12 State the use of each of the following memory (05 marks)
i. Cache memory
ii.Firmware
iii.Buffer
iv.CMOS
v.Virtual memory
13 (a) Define the term machine cycle? (01 marks)
(b) Briefly describe each of these operations of the machine cycle (04 marks)
i. Fetching
ii.Decoding
iii.Executing
iv.Storage
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EXERCISES
• Explainthemeaningof the followingterms usedin computer storage
(i) Writing(ii) Reading(ii) Storagecapacity (iii) Storagemedium(iv) Storage device(v) Access time (vi)Access
method(vii)Transfer rate(viii) cache memory(ix) flash memory(x) virtual memory(xi) onlinestorage
• Whatis the differencebetween primaryand secondarystorage?
• Distinguishbetweenrandomandsequentialmodesof access usedin storagemedia
• Explain some forms of primary memorythat ensure properperformanceof a computer
• Distinguishbetweenremovableandfixed storage
• With examplesexplainthe termprimary memory
• Statethe differencebetweenRAMandROM
• With examples,explainthe differencebetweenvolatileand non-volatilememory
• Explainthefollowingtechnologiesusedin computerstorage
a)
b)
c)
Solid state technology
Optical technology
Magnetictechnology
• State threeadvantagesof DVDs over compact discs
• Statethe four ways you wouldcare for optical storagemedia
• Whatfactors wouldyou considerbeforebuying storage mediafor use?
• Howmany bits are in the characters that form your surname?
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1. Calculate the size in bytes that a file of 5 kilobytes can occupy
on a disk.
2. John wants to transfer video clips of capacity 2GB. How many
compact discs does he need? (03 marks)
3. Estimate the number of CD-R’s (compact disk recordable)
which will be needed to make a backup of a folder occupying
2.5 GB on the hard disk of a computer.
4. Teo’s network access speed is six megabytes per second.
How many kilobytes does Teo’snetwork receive or send per
second? (02 marks)
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Central Processing Unit
The CPU is the primary
component of a
computer that processes
instructions.
It processes the data
and produces output,
which may stored or
displayed on the screen.
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The CPU mounted onto the computer
motherboard
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Components of a CPU
ACPU consists of three main
parts which include the
following;
1. Control Unit (CU)
2. Arithmetic Logic Unit (ALU)
3. Registers (and other
memories)
• Control unit
This is a part of the CPU
that tells the rest of the
computer system how to
carry out programs
instruction, i.e. directs the
movement of electronic
signals between ram and
input and output devices.
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• Arithmetic logic unit
It performs arithmetic
operations(addition,
subtraction, multiplication
and division) and logic
operation on data.
• Register/ other memories
Registers are temporary high
speed storage area that
holds data and instructions
that are being used shortly by
the computer.
• Cache memory(L1)
Cache memory is a high speed memory CPU to keep
frequently used data and instructions during program
execution.
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Functions of CPU
• To perform arithmetic, logical and comparison operations
on data and instructions.
• To decode program instructions.
• To fetch data and program instructions from memory.
• To control functions of other hardware components.
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
HOW TO CARE FOR HARDWARE
Don’t eat anything while you are working with the computer.
Install theAnti-virus software.
Check unknown files that you receive over internet.
Keep away magnet from the computer’s hardware.
Don’t keep your computer in the moist temperature.
Protect your computer from the voltage deviation.
Make sure that the wires of the computer plugged correctly.
Don’t keep heavy or huge things on the keyboard or mouse.
Keep away eatables or drinks of any type.
Make your computer protected from the dust.
Don’t unplug the system while it is running.
Keep the system firewall enabled.
Don’t keep floppy disk or CD disk in the sun.
Keep the hardware protected from jerks.
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EXERCISE
• What is a CPU?
• State the parts that make up the CPU
• Describe a five functions of the CPU
• Compare the roles of theALU and the control unit in the CPU
• Explain the roles of the different Registers found in the CPU
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Activity 2.1: Parts of a computer
• Discuss and identify whether use of each of the devices in Figure
2.1 is an input, output, storage, communication or processing
device and summarize your findings in the table below
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Activity 2.2: Categories of computer
hardware
1. What is the difference between a soft copy and a hard
copy? Give examples to support you answer.
2. Move around the computer laboratory or any office in
your school and identify other computer hardware
devices other than those mentioned in figure 2.1.
Summarize their details in terms of name, features,
function and category.
3. Identify at least one device in each category and
demonstrate how it works.
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Assembling a Computer System
• At the beginning of this chapter, you looked at hardware
devices which can be categorized as
input devices like mouse, keyboard, microphone,
camera;
output devices like monitor, printer, projector,
speakers;
storage devices like hard disks, flash disks compact
disks;
processing devices like a CPU.
• Some of these devices are summarized in figure 2.2.
below
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• When these devices are connected together, they make a
computersystem.
• For a computer system to work well, the above hardware
devices must be connected properly.
For instance,
• Akeyboard, mouse, monitor should be connected to the
System unit; the system unit and the monitor are then
connected to power either directly to the sockets or through a
UPS by use of power cables.
• If you are setting up a newly purchased computer, you will
probably find a how-to guide or a user guide in the packaging
that includes step-by-step details.
• However, even if it does not include instructions, you can still
TR. David few easyDept-STSSN set up
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Activity 2.3:Assembling a Computer System (Desktop)
Write down any key steps followed to assemble a computer system
i.
ii.
Check whether all the devices required are available.
Locate the monitor cable. It will usually be either a VGAor DVI
cable. VGAcables will often have blue connectors to make them
easier to identify.
iii. Connect one end of the cable to the monitor port on the back of the
computer case and the other end to the monitor. Hand-tighten the
plastic-covered screws on the monitor cable to secure it.
iv. Connect other devices by critically looking at the port types.
v. Locate the power supply cables. Plug the first power supply cable
into the back of the computer case, and then into a surge protector.
Then, using the other cable, connect the monitor to the surge
protector.
vi. Finally, plug the surge protector into a wall outlet. You may also need
to turn the surge protector on if it has a power switch.
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What precautions must be taken while assembling a
computer system?
• Fully shut down and unplug the computer before you make any
attempts to assemble the computer especially the system case
components.
• Take off any metal objects on your arms or fingers such as
bracelets, rings or watches. Even if your unit is unplugged, there
may still be some remaining electric charge.
• Make sure your hands are completely dry to avoid damaging any
mechanical parts as well as to avoid electrocution.
• Work in a cool area to avoid perspiration for the same reason as
seen in the previous number.
• Before touching any part within the system case, put your hands
against another metal surface (such as the computer casing) to
remove static charge, which may damage sensitive devices.
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• Prepare a place to keep any screws you may remove.Acontainer or
piece of paper with labels for each part (casing, motherboard, CD
drive, etc) is ideal to avoid confusion between the similar-looking
screws.
• Handle all parts with care. Place each piece you remove carefully
down onto a stable surface.
• If a component does not come out easily, do not forcefully remove it.
Instead, check that you are removing it correctly and that no wires or
other parts are in the way.
• Be careful when holding the motherboard, it’s underside actually
quite pointy and able to hurt you.
• Never attempt to remove the power source, a box attached to the side
or bottom of the unit to which all cables are connected.
• When removing any cables, wires or ribbons, make sure to grasp the
wire at the base or head to keep it from breaking.
• Be careful not to drop any small parts (particularly screws) into
unreachable areas such as into the computer fan or disk drive.
• Take note that the three of the most damaging things to a computer
are moisture (sweat, drinking water), shock (electric or from being
dropped) and dust (any debris from household dust to bits of food).
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Setting up a laptop computer
If you have a laptop, setup should be very easy.
i. Just open it up and press the power button.
ii. If the battery is not charged, you will need to plug in
theAC adapter and charge it before using it.
iii. If your laptop has any peripherals, such as external
speakers, mice, keyboard you will connect the
same way as desktop computers, since laptops and
desktops generally use the same types of
connections.
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Starting and Shutting down a Computer System
• After assembling a computer, the next step is how it can be
powered on correctly, used and then shut down with proper
procedures.
• The process of starting a computer is called booting.
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Starting the computer:
• Make sure all the plugs are well connected.
• Switch on the electricity socket and the Uninterruptible Power
Supply Unit.
• Press the power button on the computer monitor first. It should
show signal.
• Press the power button on the system unit.
• The computer should now start to boot and load windows.
• If the welcome screen appears, select your username and enter
the password.
• The Desktop should now appear.
• Give it time to load the elements and start up programs.
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Shutting down a Computer System
• Turn off Computer (power) option
is located on the Start menu as
shown in figure 2.4.
• The Turn off Computer (power)
dialog has the
i.
ii.
Sleep/ Standby / Hibernate
option,
Shutdown option
iii. Restart Options.
• Log Off and Switch User options
are also located on the Start
menu.
• ,
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Activity 2.4: Starting and shutting down a
computer system
1. Explain the logical order of switching on the assembled
computer system and how it can be shut down properly.
2. Stating from a fully connected computer system, demonstrate
how a computer can be switched on and later switched off after
use.
3. What precautions MUST be considered in 2. above.
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Activity of Integration
• Sazamwe Secondary School is planning to have a careers day to
sensitize S.1 students about the importance of vocational
subjects.
• The 100 students of S.1 will assemble in the main hall which has
a power supply. The career’s teacher will share pictures and
videos showing areas where various subjects are applicable.
Task
Advise the career’s teacher on which computer hardware devices
will be needed and how they work to support her presentation to
the students.
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Chapter Summary
In this chapter, you have learnt about:
a) the physical devices of a computer system and how each
operates.
b) how to assemble a computer system.
c) safely starting and shutting down a computer system.
d) using computer peripheral tools.
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