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Unit 4
Introduction to Computer
Architecture
There are different types of Notebook (size of a
computer of varying size sheet of notebook
and power, including the paper)
following: Hand held (can be held
Supercomputer (the most in one hand)
powerful type of Pen-based (main
mainframe) input device is an
electronic pen)
Mainframe (large, very PDA (personal digital
powerful, multi-user i.e.can assistant, has
be used by many people at function such as task
the same time, multi-tasking lists, diary, address
i.e. can run many programs book)
and process different sets of Note that the term PC
data at the same time) usually refers to an IBM
Minicomputer (smaller than Compatible personal
a mainframe, powerful, computer i.e. an Apple Mac
multi-user, multi-tasking) personal computer is not
referred to as a PC. A
Personal computer (PC) computer that provides a

2. (single user) Desktop service on a network e.g.
computer (suitable size for storing files, sharing a
sitting on an office desk) printer, is known as a server
Workstation (most computer. Server
powerful type of Computers usually have a
desktop, used for UPS (uninterruptible power
graphic design, etc.) supply) attached to them.
Portable (can be carried This is a battery that
around, can operate with automatically provides an
batteries) electricity supply to allow
Laptop (large portable, the server to shut itself
can be rested on user’s down properly if the main
lap) supply fails.
The processor e.g.
Pentium, is the most
important part of the
computer. It processes the
data and controls the

3. computer. Powerful hard disk, CD-ROM, CD-R
computers used as servers disks, CD-RW disks, DVDs
often have more than one and MO disks, A common
processor. There are tow Communications device
main types of memory: is a modem (a modulator/
a RAM (random access demodulator used for
memory) holds the converting Digital signals to
program instructions analogue signals and vice
and the data that is versa ในทำงกลับกัน to
being used กำำลังถูกใช้ allow a computer to be
by the processor. connected to the ordinary
b ROM (read only telephone system).
memory) holds the A set of connector used
program instructions for carrying signals between
and settings required to the different parts of a
start up the computer Computer is known as a
bus, Data is transferred
The combination of the constantly between the
processor and memory is processor and memory
sometimes referred to as along the system bus. Each
the CPU (central processing part of memory has its own
unit), although sometimes memory address determines
the processor itself is where processed data is
referred to as the CPU. The stored ถูกเก็บ by sending an
other parts connected to the address signal along an
CPU are known as( periph address bus and data along
erals.อุปกรณ์เสริม )These a data bus. This is
can include input devices, synchronized by an
output devices, storage electronic clock in the CPU
devices and that determines the
communications devices. operation speed of the
Input devices include: processor. Transferring data
keyboards, scanners, between the processor and
barcode readers, digital RAM can slow up the

4. cameras, microphones and computer; therefore, some
video cameras e.g. very expensive, extremely
webcams (small digital fast memory is usually used
video cameras used on the as a cache to hold the most
Web). Output devices frequently used data.
include: monitors (VDU In a desktop computer,
display screens) printers, the CPU (central processing
plotters, loudspeakers, unit) and storage devices
headphones. Storage (pieces of equipment used
devices include: magnetic for
tape , floppy disks
(diskettes),

5. reading from and writing to American spelling of disk is
a storage medium) are commonly used, although
normal built inside a system the British spelling, disc, is
unit which consists of a sometimes used. Before a
metal chassis enclosed in a program or data can be
flat desktop or a tower used, it must be transferred
shaped case. Other from the Storage device to
peripherals are attached to the main RAM memory.
the system unit by cables. Hard disks consist of a set
Each peripheral uses its own of magnetic coated metal
driver card or controller (an disks that are vacuum-
expansion card that is sealed inside a case to keep
plugged ถูกเสียบ into special out the dust. The magnetic
expansion slots in the surfaces of the disks are
system unit). Expansion formatted using a
cards contain the read/write head to provide
electronics required to magnetic storage areas.
communicate with and These storage areas form
control the device e.g. video concentric circles called
or graphics cards are used tracks and each track is
for monitors, soundcards subdivided into sections
are used for audio called sectors. The disks are
input/output and NICs rotated at high speed and
(network interface cards) read from or written to by
are used for connection to the read/write head that
other computers in a moves across the surface of
network (computing devices the disks, In server
connected together). Extra computers, hard disks can
memory can also be added be connected together and
to the computer using made to operate as one unit
special memory expansion using RAID (a redundant
slots inside the computer. A array of inexpensive disks).
portable computer that does This can speed up the
not have enough space system and provide a way

6. inside to fit expansion cards of recovering data if the
may use an external device system crashes (fails
called a port replicator to suddenly and completely,
provide connections for usually referring to the
peripherals. failure of a hard disk). there
Storage devices in the is a variety of optical
form of a disk or tape are storage devices that use
used to store the programs laser light to read or write
and data that are not being to a disk, including: CD-
used, Note that the ROMs (compact disk read
only memory), CD-R
(recordable

7. compact disk), CD-RW a multiple of the speed of
(rewritable compact disk), the first devices produced
DVD (digital versatile disk- e.g. CD-ROM, DVD (given
previously known as digital as a multiple of the speed
video disk). of the first devices
An input device called a produced e.g. 24x = 24
barcode reader is a special times, 12x = 12 times)
type of scanner for reading e The display monitor size
barcodes (a set of printed (measured in inches
bars of varying thickness diagonally across the
that are used to identify a screen surface)
product e.g. used to price f the monitor image
items in supermarkets) quality (resolution) given
When comparing by the number of pixels
computers, the power of the (picture elements) that
computer is important. This are used across and
is mainly determined by the down the screen e.g.
speed and capacity (size) of 800x600, or by the
each part of the computer. graphics standard used
Speed is measured in e.g. VGA (video graphics
hertz (Hz) i.e. cycles per array), SVGA (super video
second graphics array)
Capacity is measured in g the graphics card
bytes (B) where 1 byte = 8 memory size (MB-
bits (binary digits) = 1 megabytes)
character. When specifying h the speed of the modem
a computer the following (measured in kbps-
are normally quoted: kilobits per second)
a the speed of the
processor (MHz - Two different number
megahertz, GHz - systems are used in
gigahertz) b the computer specifications:
capacity (size) of the A The decimal system,
memory (MB-megabytes) which consists of the

8. c the capacity (size) of digits from 0 of 9, is used
the magnetic storage for measuring speed.
devices e.g. hard disk, B The binary system,
floppy disk (MB- which only has two digits
megabytes, GB- (1 and 0), is used for
gigabytes) measuring capacity.
d the speed of the optical
storage devices e.g. CD-
ROM, DVD (given as

9. The following prefixes are Communication is provided
also used in measurements: between applications
programs (wordprocessors,
drawing programs, etc.) and
the computer hardware (the
physical components of a
computer system) by a set
of programs collectively
known as the operation
system e.g. Microsoft
Windows, MacOS.
(Glendinning, 2002, pp
14-16)

10. Deci
mal
syste
m
Binar
y
syste
m
Kilo
103
=1
thou
sand
210 =
1,02
4
Meg
a
106
=1
millio
n
220 =
1,04
8,57
6
Giga
109
=1
thou
sand
millio
n
230 =
1,07
3,74
1,82
4

11. Task 1 What do these abbreviations mean?
1. CD-ROM
_______________________________________________
_______.
2. RDRAM
_______________________________________________
_______.
3. MB
_______________________________________________
_______.
4. GHz
_______________________________________________
_______.
5. NICs
_______________________________________________
_______.
6. SDRAM
_______________________________________________
_______.
7. PDA
_______________________________________________
_______.
8. UPS
_______________________________________________
_______.

12. 9. DVD
_______________________________________________
_______.
10. RAID
_______________________________________________
_______.

13. Task 2 Match each item in column A with its function in
Column B. Then describe its function in two ways as given
example.
A : Item B : Function
_________ 1.RAM a) controls the cursor
_________ 2.Processor
b) inputs data through keys
_________3.Mouse
like a typewriter
_________4.Clock
_________5. 3.5” floppy c) displays the output from a
drive computer on a screen
_________6. monitor
d) reads DVD-ROMs
_________7. keyboard
_________8. DVD-ROM e) reads and write to
drive removable magnetic disks
_________9. cache
f) holds data read or written
_________10. ROM
to it by the processor
i) g) provides extremely fast
access for sections of a
program and it data
h) controls the timing of
signals in the computer
i) controls all the operation
in a computer
j) stores the processed data

14. Task 3 Describe its function in two ways as given
example
1. Using the present simple
- RAM holds data read or written to it by the
processor.
2. Emphasizing the function
- The function of ROM is to hold data read or
written to it by the processor.
Processor
1. Processor controls all the operation in a
computer.
2. The function of Processor is to controls all the
operation in a computer.
Mouse
1. Mouse controls the cursor.
2. The function of Mouse is to controls the
cursor.
Clock
1. Clock controls the timing of signals in the
computer.
2. The function of Clock is to controls the timing of
signals in the computer.
3.5” floppy drive
1. Floppy drive reads and write to removable
magnetic disks.
2. The function of floppy drive is to reads and write
to removable magnetic disks.
Monitor
1. Monitor displays the output from a computer on a
screen.
2. The function of Monitor is to displays the output
from a computer on a screen.
Keyboard

15. 1. Keyboard inputs data through keys like a
typewriter.
2. The function of Keyboard is to inputs data
through keys like a typewriter.
DVD-ROM drive
1. DVD-ROM drive reads DVD-ROMs.
2. The function of DVD-ROM drive is to reads DVD-
ROMs.
ROM
1. ROM stores the processed data.
2. The function of ROM is to stores the processed
data.
Task 4 Describe the function of an item in two ways as
the example given.
1. Used to-infinitive
ROM is used to hold instructions which are
needed to start up the computer.
2. Used for +-ing form
ROM is used for holding instructions which are
needed to start up the computer.
RAM
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
Processor
1.
_______________________________________________
_______.

16. 2.
_______________________________________________
_______.
Mouse
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
Clock
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
3.5” floppy drive
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
Monitor
1. displays the output from a computer on a screen

17. 2.
_______________________________________________
_______.
Keyboard
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
DVD-ROM drive
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
Cache
1.
_______________________________________________
_______.
2.
_______________________________________________
_______.
Read the following passage

18. Basic elements
At a top level, a computer consists of processor, memory,
and input/output (I/O) components, with one or more
modules of each type. These are interconnected in some
fashion to achieve the main function of the computer,
which is to execute programs, Thus, there are four main
structural elements :
• Processor: Controls the operation of the computer
and performs its data processing functions. When
there is only one processor, it is often refered to as
the central processing unit. (CPU)
• Main memory: Stores data and programs, this
memory is typically volatile; it is also referred to as
real memory or primary memory.
• I/O modules : Move data between the computer
and its external environment. The external
environment consists of a variety of external
devices, including secondary memory devices.
Communication equipment and terminals.
• System bus : Some structure and mechanism that
provides for communication among processors,
main memory, and I/Q modules
(Stalling
s, 2001)
Task 5 Complete the following statements by using
information from the passage.
1. The passage is
about__________________________________________
______.
2. The functions of operating system are
2.1

19. _______________________________________________
________________.
2.2
_______________________________________________
________________.

20. 3. A computer consists of
______________________________________________.
4. CPU is often referred to
______________________________________________.
for
controlling_______________________________________
________________.
_______________________________________________
____________________.
5. I/O modules referred to
_________________________________________which
is used to
A computer is a device which enables you to
process information (1) automatically and (2) in
3 accordance with instructions the you give it
(1) means that it can carry out capture-process-
store-communicate all by itself, or at least with
the minimum of human intervention. It dose
6 this be means of hardware, and communication
devices, linked together electronically.
(2) means the it can be adapted to carry out
almost any kind of information processing task,
9 whether word processing or stock control. It
does this by means of software, i.e. set of
instructions or programs which control these
hardware device so that carry out the required
operation on the information
(Carter, 1991).
Task 6 Answer the following questions:
1. What is the topic of this extract?

21. _______________________________________________
____________________.
2. What is the main idea?
_______________________________________________
____________________.
3. Write down the means to process information
automatically.
(1)
_______________________________________________
_
(2)
_______________________________________________
_
(3)
_______________________________________________
_
(4)
_______________________________________________
_
4. Write down the accordance with instructions.
(1)
_______________________________________________
_
(2)

22. _______________________________________________
_
5. Find the reference for the words below
(1) which (line 1)
___________________________________
(2) this (line 4)
___________________________________
(3) this (line 7)
___________________________________
(4) programs (line 8)
___________________________________
6. What are the functions of the programs?
_______________________________________________
____________________
Computer System Components
Computer system hardware components include
devices that perform the functions of input, processing,
data storage and output.
In computer system, processing is accomplished by
interplay between one or more of the central processing
units and primary storage. Each central processing unit
(CPU) consists of three associated elements; the
arithmetic/logic unit, the control unit, and the register
areas. The arithmetic/logic unit (ALU) performs
mathematical calculations and makes logical comparisons.
The control unit sequentially accesses program instruction,
decodes them, and coordinates the flow of data in and out
of ALU, the registers, primary storage and even secondary

23. storage and various output devices. Registers are high-
speed storage areas used to temporarily hold small units
of program instructions and data immediately, during and
after execution by the CPU
Primary storage, also called main memory or just
memory, with the CPU. Memory holds program
instructions and data immediately before of immediately
after the registers. (Stair, 1996).

24. Task 7 Answer the following questions.
1. Write down the components devices of computer
hardware system
(1)
_______________________________________________
_
(2)
_______________________________________________
_
(3)
_______________________________________________
_
(4)
_______________________________________________
_
2. Write down the elements of central processing
unit (CPU)
(1)
_______________________________________________
_
(2)
_______________________________________________
_
(3)
_______________________________________________
_

25. 3. Complete the figure by using the information
given
Input devices
Communication devices
Output devices
Processing devices
Control unit
Arithmetic logic unit
Register storage area

26. Central processing unit (CPU)
The central processing unit is the heart of any
computer system. It is in the central processing unit that
programs are executed. All data that are operated on by a
program must be copied into the CPU (although not
necessarily at the same time).
The CPU can be viewed as consisting of three main
components. These are:
1. The control unit
2. The arithmetic and logic unit
3. The storage unit
The control unit consists of hardware that can monitor
the operation of the CPU itself. It initiates and controls the
flow of data and instructions within the CPU. It interprets
those instructions to be executed and the physically
implements what ever actions are necessary to carry out
the execution of those instruction.
The arithmetic and logic unit carries out the arithmetic
operations determined by the control unit. It also can
make comparisons between data to determine if they are
equal or unequal, or if one piece of data is greater than,
or less than another piece of date.
The storage unit consists of memory locations. It is
also called primary memory (to differentiate if from
secondary storage). It is also frequently called core. This
term relates to a no longer used memory technology that
used tiny ferrite core as the basic memory unit.
(William, & Sawyer,
2001).
Task 8 Complete the figure below

27. Task 9 Answer the following question:
1. What is the best topic of this extract?
________________________________________
___________________________
2. What is the main idea?
_______________________________________________
____________________
3. What are the components of CPU.
________________________________________
___________________________
4. What are the components perform the execution
of an instruction.
________________________________________
___________________________
5. What are the functions of arithmetic and logic
unit?
(1)
_______________________________________________
_
(2)
_______________________________________________
_
(3)
_______________________________________________
_

28. CPU Characteristics
Machine cycle time
Because having efficient processing and timely output
is important, organizations use a variety of measures to
gauge processing speed. These include the time it takes to
complete one machine cycle, clock speed, and others.
Machine cycle time. The execution of an instruction
takes place during a machine cycle. The time in which a
machine cycle occurs is measured in fractions of a second.
Machine cycle time range from milliseconds (one
thousandth of one second) and microseconds (one
millionth of one second) for smaller computer to
nanoseconds (on billionth of one second) and picoseconds
(one trillionth of one second) for the larger ones. Machine
cycle time also can be measured in terms of how many
instructions are executed in a second. This measure,
called MIPS, stands for millions of instructions per second.
MIPS is used to measure speed for computer systems of
all sizes
Another measure of machine cycle time is a FLOP, or
floating – point operation. A floating – point operation is
an arithmetic calculation where the decimal point “floats”
or moves to provide greater accuracy during computing.
Megaflop, millions of floating-point operations per second
and gigaflop, millions of floating-point operations per
second, are popular measures for large computer systems.
(Ralph. 1996).
Task 10 Complete the following statements.
1. Give the definition of each word.
a.

29. Milliseconds_______________________________
_____________________
b.
Microseconds_____________________________
_____________________
c.
Nanoseconds_____________________________
_____________________
d.
Picoseconds______________________________
_____________________

30. 2. Write down 3 kinds of machine cycle time
measurements
a.
_______________________________________________
_______________
b.
_______________________________________________
_______________
c.
_______________________________________________
_______________
Clock speed
Each CPU produces a series of electronic pulses at a
predetermined rate, called the clock speed, which effects
machine cycle time. The control unit portion of the CPU
controls the various stages of the machine cycle by
following predetermined internal instructions, know as
microcode. The control unit executes the microcode in
accordance with the electronic cycle or pulses of the CPU
“clock”. Each microcode instruction takes at last the same
amount of time to occur as the interval between pulses.
The shorter the interval between pulses, the faster each
microcode instruction can be executed.
Clock speed is often measured in megahertz. A hertz
is one cycle or pulse. Megahertz (MHz) is the
measurement of cycles in millions of cycles per second.
The clock speed for personal computers can’ range from
about 20 MHz too 100 MHz or more. (Ralph. 1996).
Task 11 Complete the following statements.

31. 1. Clock speed refers to
_______________________________________________
_______________________________________________
____________________
2. Microcode refers to
_______________________________________________
__
_______________________________________________
____________________
3. The advantage of the shorter interval between
pluses is _________________
_______________________________________________
____________________
4. Hertz refers
to_____________________________________________
__________
_______________________________________________
____________________
5. MHz stands for ___________________________,
and refers to______________
_______________________________________________
____________________
Word length and bus line width

32. Data is moved around within a computer system, not
in a continuous stream, but in groups of bits. A bit is a
binary digit – 0 or 1. Therefore, another factor affecting
overall system performance, and particularly speed, is the
number of bits the CPU can process at any one time. This
number of bits is called the word length of the CPU. A CPU
with a word length of 32 (called a 32 – bit CPU) will
process 32 bits of data in one machine cycle.
Data is transferred from the CPU to other system
components via bus lines, the physical wiring that
connects the computer system components. The number
of bits a bus line can transfer at any one time is known as
bus line width. (Ralph, 1996)
Task 12 Complete the statements below.
1. “Bit” stands for ____________and refers to
_____________________________
_______________________________________________
____________________.
2. The number of bits is affected
by______________________________________
____________and_____________________.
3. Wordlength of the CPU
means________________________________________
which ________________________in one
machine cycle.
4. “Bus line width” refers to
_____________________________________________

33. _______________________________________________
____________________
5. “Bus line”
means._________________________________________
__________
_______________________________________________
____________________

34. Language focus
Word formation: prefixes
When you are reading, you will come across unfamiliar
words. It is often possible to guess the meanings of these
words if you understand the way words in English are
generally formed.
Prefix stem suffixes
An English word can be divided into three parts: a prefix,
a stem, and a suffix. Pre-means ‘before’. A prefix,
therefore, is what comes before the stem. Consider. As an
example, the prefix de- (meaning ‘reduce’ of ‘reverse’) in
a word like demagnetize (meaning ‘to deprive of
magnetism’). A suffix is what is attached to the end of the
stem. Consider, as an example, the suffix-er (meaning
‘someone who’) in programmer (‘a person who program’).
Suffixes change the word from one part of speech to
another. For example, -ly added to the adjective quick
gives the adverb quickly. Prefixes, on the other hand,
usually change the meaning of the word. For example, un-
changes a word to the negative, Unmagnetizable means
‘not capable of being magnetized’. Let us now consider
some prefixes, their usual meanings, and how they
change the meanings of English words.

35. Prefixes
Negati Size Locatio Time Number
ve and n and
positiv order
e
un- semi- inter- pre- mono-
non- mini- super- ante- bi-
in- micro- trans- fore- hex-
dis- ex- post- oct-
re- extra- multi-
peri-
Study these tables. Try to find additional examples, using
your dictionary if necessary.
1 Negative and positive prefixes:
Prefix Meaning Examples
Negative un-
unmagnetized
im- incomplete
i- not impossible
il- illegal
ir- irregular,
irrelevant
non- not connected with non-
programmable,
mis- bad, wrong misdirect
mal- malfunction
dis- opposite feeling disagree
opposite action disconnect
anti- against antiglare

36. de- reduce, reverse demagnetize,
decode
under- too little underestimate
Positive re- do again reorganize
over- too much overload
2 Prefixes of size :
Prefix Meaning Examples
semi- halt, partly semiconductor
equi- equal equidistant
mini- small minicomputer
micro- very small microcomputer
macro- large, great macroeconomics
mege- megabyte
3 Prefixes of location:
Prefix Meaning Examples
inter- between, among interface, interactive
super- over supersonic
trans- across transmit, transfer
ex- out exclude, extrinsic
extra- beyond extraordinary
sub- under subschema
infra- below infra-red
peri- around peripheral
4 Prefixes of time and order:
Prefix Meaning Examples
ante- before antecedent
pre- prefix
prime- first primary, primitive
post- after postdated
retro- backward
retroactive

37. 5 Prefixes of numbers:
Prefix Meaning Examples
semi- half semicircle
mono- one monochromatic
bi- two binary
tri- three triangle
quad- four quadruple
penta- five pentagon
hex- six hexadecimal
sept(em)-seven September
oct- eight octal
dec- ten decimal
multi- many multiplexor
6 Other prefixes:
Prefix Meaning Examples
pro- before, in advance program
forward progress
auto- self automatic
co- together, with co-ordinate
con- connect
Task 13 Read the following sentences and circle the
prefixes. For each word that has a prefix, try to decide
what the prefix means. Refer back to the table if you need
help.
1 Floppy disks are inexpensive and reuseable.
2 If a printer malfunctions, you should check the
interface cable.
3 The multiplexor was not working because
someone had disconnected it by mistake.
4 Improper installation of the antiglare shield will
make it impossible to read what is on the screen.

38. 5 After you transfer text using the ‘cut and paste’
feature, you may have to reformat the text you
have inserted.
6 You can maximize your chances of finding a job if
you are bilingual or even trilingual.
7 Peripheral devices can be either input devices
(such as keyboards) or output devices (such as
printers).
8 Your pay rise is retroactive to the beginning of
June and you will receive a biannual bonus.
9 The octal and hexadecimal systems are number
systems used as a form of shorthand in reading
groups of four binary digits.
10As the results are irregular, the program will have
to be rewritten.
Task 14 Fill in the gaps with the correct prefix from the
following list.
auto de
dec inter
maxi mega
micro mini
mono multi
semi sub
1 Most people prefer a color screen to a
__________ chrome screen.
2 __________script is a character or symbol written
below and to the right of a number or letter,
often used in science.
3 A __________byte equals approximately on
million bytes.

39. 4 Once you finish your program, you will have to
test it and __________ bug it to remove all the
mistakes.
5 The introduction of __________ conductor
technology revolutionized the computer industry.
6 If a computer system has two or more central
processors which are under common control, it is
called a __________ processor system.
7 The __________ system is a number system
with a base of 10.
8 When the user and the computer are in active
communication on a graphics system, we refer to
this as __________ active graphics.
Conclusion
Through this unit you have learnt briefly the
different types of computers and theirs capabilities. Note
that a computer consists of processor, memory and I/O
which interconnected to execute programs. Also, you have
figured out the specific information of computer elements,
functions and interconnection. According to the physical
components of computer system and any supporting
equipment, the heart of any computer system is the
central processing unit, or CPU. To focus on the CPU
operation, you must understand machine cycle time and
FLOP which a machine cycle occurs is measured in
fractions of a second.