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Unit 4Introduction to Computer

Architecture

There are different types of computer of varying size and power, including the following:Supercomputer (the most powerful type of mainframe)

Mainframe (large, very powerful, multi-user i.e.can be used by many people at the same time, multi-tasking i.e. can run many programs and process different sets of data at the same time)

Minicomputer (smaller than a mainframe, powerful, multi-user, multi-tasking)

Personal computer (PC)

Notebook (size of a sheet of notebook paper)Hand held (can be held in one hand)

Pen-based (main input device is an electronic pen) PDA (personal digital assistant, has function such as task lists, diary, address book)

Note that the term PC usually refers to an IBM Compatible personal computer i.e. an Apple Mac personal computer is not referred to as a PC. A computer that provides a

(single user) Desktop computer (suitable size for sitting on an office desk)

Workstation (most powerful type of desktop, used for graphic design, etc.)

Portable (can be carried around, can operate with batteries)

Laptop (large portable, can be rested on user’s lap)

service on a network e.g. storing files, sharing a printer, is known as a server computer. Server Computers usually have a UPS (uninterruptible power supply) attached to them. This is a battery that automatically provides an electricity supply to allow the server to shut itself down properly if the main supply fails.

The processor e.g. Pentium, is the most important part of the computer. It processes the data and controls the

computer. Powerful computers used as servers often have more than one processor. There are tow main types of memory:a RAM (random access

memory) holds the program instructions and the data that is being used กำำลังถูกใช้ by the processor.

b ROM (read only memory) holds the program instructions and settings required to start up the computer

The combination of the processor and memory is sometimes referred to as the CPU (central processing unit), although sometimes the processor itself is referred to as the CPU. The other parts connected to the CPU are known as( peripherals.อุปกรณ์เสริม )These can include input devices, output devices, storage devices and communications devices. Input devices include: keyboards, scanners, barcode readers, digital

hard disk, CD-ROM, CD-R disks, CD-RW disks, DVDs and MO disks, A commonCommunications device is a modem (a modulator/demodulator used for converting Digital signals to analogue signals and vice versa ในทำงกลับกัน to allow a computer to be connected to the ordinary telephone system).

A set of connector used for carrying signals between the different parts of a Computer is known as a bus, Data is transferred constantly between the processor and memory along the system bus. Each part of memory has its own memory address determines where processed data is stored ถูกเก็บ by sending an address signal along an address bus and data along a data bus. This is synchronized by an electronic clock in the CPU that determines the operation speed of the processor. Transferring data between the processor and RAM can slow up the

cameras, microphones and video cameras e.g. webcams (small digital video cameras used on the Web). Output devices include: monitors (VDU display screens) printers, plotters, loudspeakers, headphones. Storage devices include: magnetic tape , floppy disks (diskettes),

computer; therefore, some very expensive, extremely fast memory is usually used as a cache to hold the most frequently used data.

In a desktop computer, the CPU (central processing unit) and storage devices (pieces of equipment used for

reading from and writing to a storage medium) are normal built inside a system unit which consists of a metal chassis enclosed in a flat desktop or a tower shaped case. Other peripherals are attached to the system unit by cables. Each peripheral uses its own driver card or controller (an expansion card that is plugged ถกูเสียบ into special expansion slots in the system unit). Expansion cards contain the electronics required to communicate with and control the device e.g. video or graphics cards are used for monitors, soundcards are used for audio input/output and NICs (network interface cards) are used for connection to other computers in a network (computing devices connected together). Extra memory can also be added to the computer using special memory expansion slots inside the computer. A portable computer that does not have enough space

American spelling of disk is commonly used, although the British spelling, disc, is sometimes used. Before a program or data can be used, it must be transferred from the Storage device to the main RAM memory. Hard disks consist of a set of magnetic coated metal disks that are vacuum-sealed inside a case to keep out the dust. The magnetic surfaces of the disks are formatted using a read/write head to provide magnetic storage areas. These storage areas form concentric circles called tracks and each track is subdivided into sections called sectors. The disks are rotated at high speed and read from or written to by the read/write head that moves across the surface of the disks, In server computers, hard disks can be connected together and made to operate as one unit using RAID (a redundant array of inexpensive disks). This can speed up the system and provide a way

inside to fit expansion cards may use an external device called a port replicator to provide connections for peripherals.

Storage devices in the form of a disk or tape are used to store the programs and data that are not being used, Note that the

of recovering data if the system crashes (fails suddenly and completely, usually referring to the failure of a hard disk). there is a variety of optical storage devices that use laser light to read or write to a disk, including: CD-ROMs (compact disk read only memory), CD-R (recordable

compact disk), CD-RW (rewritable compact disk), DVD (digital versatile disk-previously known as digital video disk).

An input device called a barcode reader is a special type of scanner for reading barcodes (a set of printed bars of varying thickness that are used to identify a product e.g. used to price items in supermarkets)

When comparing computers, the power of the computer is important. This is mainly determined by the speed and capacity (size) of each part of the computer.

Speed is measured in hertz (Hz) i.e. cycles per second

Capacity is measured in bytes (B) where 1 byte = 8 bits (binary digits) = 1 character. When specifying a computer the following are normally quoted:a the speed of the

processor (MHz - megahertz, GHz - gigahertz) b the capacity (size) of the memory (MB-megabytes)

a multiple of the speed of the first devices produced e.g. CD-ROM, DVD (given as a multiple of the speed of the first devices produced e.g. 24x = 24 times, 12x = 12 times)

e The display monitor size (measured in inches diagonally across the screen surface)

f the monitor image quality (resolution) given by the number of pixels (picture elements) that are used across and down the screen e.g. 800x600, or by the graphics standard used e.g. VGA (video graphics array), SVGA (super video graphics array)

g the graphics card memory size (MB-megabytes)

h the speed of the modem (measured in kbps-kilobits per second)

Two different number systems are used in computer specifications:A The decimal system,

which consists of the

c the capacity (size) of the magnetic storage devices e.g. hard disk, floppy disk (MB-megabytes, GB-gigabytes)

d the speed of the optical storage devices e.g. CD-ROM, DVD (given as

digits from 0 of 9, is used for measuring speed.

B The binary system, which only has two digits (1 and 0), is used for measuring capacity.

The following prefixes are also used in measurements:

Communication is provided 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)

Decimal

system

Binary

system

Kilo103

= 1 thousand210 = 1,024

Mega106

= 1 million220 = 1,048,576

Giga109

= 1 thousand million230 = 1,073,741,824

Task 1 What do these abbreviations mean?1. CD-ROM

______________________________________________________.

2. RDRAM

______________________________________________________.

3. MB

______________________________________________________.

4. GHz

______________________________________________________.

5. NICs

______________________________________________________.

6. SDRAM

______________________________________________________.

7. PDA

______________________________________________________.

8. UPS

______________________________________________________.

9. DVD

______________________________________________________.

10. RAID

______________________________________________________.

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_________ 2.Processor_________3.Mouse_________4.Clock_________5. 3.5” floppy drive_________6. monitor_________7. keyboard_________8. DVD-ROM drive_________9. cache_________10. ROM

a) controls the cursor

b) inputs data through keys like a typewriter

c) displays the output from a computer on a screen

d) reads DVD-ROMs

e) reads and write to removable magnetic disks

f) holds data read or written 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 computerj) stores the processed data

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.

Processor1. 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

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-infinitiveROM 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.

RAM1.

______________________________________________________.

2.

______________________________________________________.Processor

1.

______________________________________________________.

2.

______________________________________________________.Mouse

1.

______________________________________________________.

2.

______________________________________________________.Clock

1.

______________________________________________________.

2.

______________________________________________________.3.5” floppy drive

1.

______________________________________________________.

2.

______________________________________________________.Monitor

1. displays the output from a computer on a screen

2.

______________________________________________________.Keyboard

1.

______________________________________________________.

2.

______________________________________________________.DVD-ROM drive

1.

______________________________________________________.

2.

______________________________________________________.Cache

1.

______________________________________________________.

2.

______________________________________________________.

Read the following passage

Basic elementsAt 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

(Stallings, 2001)

Task 5 Complete the following statements by using information from the passage.

1. The passage is about________________________________________________.

2. The functions of operating system are2.1

_______________________________________________________________.

2.2

_______________________________________________________________.

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 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 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, 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?

3

6

9

___________________________________________________________________.

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)

________________________________________________

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

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).

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)

________________________________________________

3. Complete the figure by using the information given

Input devicesCommunication devicesOutput devicesProcessing devicesControl unitArithmetic logic unitRegister storage area

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 unit2. The arithmetic and logic unit3. The storage unitThe 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

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)

________________________________________________

CPU Characteristics

Machine cycle timeBecause 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.

Milliseconds____________________________________________________b.

Microseconds__________________________________________________c.

Nanoseconds__________________________________________________d.

Picoseconds___________________________________________________

2. Write down 3 kinds of machine cycle time measurements

a.

______________________________________________________________

b.

______________________________________________________________

c.

______________________________________________________________

Clock speedEach 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.

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

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

_____________________________________________

___________________________________________________________________

5. “Bus line” means.___________________________________________________

___________________________________________________________________

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.

Prefixes

Negative and positive

Size Location

Time and order

Number

un-non-in-dis-re-

semi-mini-micro-

inter-super-trans-ex-extra-peri-

pre-ante-fore-post-

mono-bi-hex-oct-multi-

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- incompletei- not impossibleil- illegalir- irregular,

irrelevantnon- not connected with non-

programmable,mis- bad, wrong misdirectmal- malfunctiondis- opposite feeling disagree

opposite action disconnectanti- against antiglare

de- reduce, reverse demagnetize, decode

under- too little underestimate Positive re- do again reorganize

over- too much overload2 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, amonginterface, 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

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.

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.

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.

ConclusionThrough 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.