Ch 1_Intro

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Introduction to

Computers

- Defnition, Characteristic, Applicable area,Evolution, History, and Classifcation ocomputers are covered in this handout.

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CHAPTER ONE: Introduction to Computers

Objective:

Define the term computer

Identify the several characteristics of computer that made them useful and popular

Identify the evolution (Generation) of computers

Application of Computers

Identify the different types of computers

1.1. What is Computer?

A computer is an electronic device that accepts data, performs computations, and

makes logical decisions according to instructions that have been given to it; then

produces meaningful information in a form that is useful to humans !he name computer

comes from a "atin #ord computator, meaning, $to compute%

1.1.1. Characteristics of computers

Department of computer science and I!

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!oday, computers are every#here & in our offices, homes, appliances, automobiles &

the list is endless 'uch of the #orld runs on computers, and computers have profoundly

changed our lives, mostly for the better !he characteristics of a computer sho# the

capability and the potential of the computer for processing data !his saves time, space,

money, labors etc And they ans#er the uestions such as *hy computers are used+ *hy

have they become so popular+ ome of the characteristics of the computer are as follo#s

Speed

!he ability of the computers to carry out their instructions in a very short period of time

is one of the main reasons for their popularity Computers can perform tasks #ithin a

matter of seconds or minutes that #ould be impossible for a person to complete by hand

in lifetime

Its speed is measured by the amount of time it took to perform or carry out a basic

operation And its speed measured in terms of micro second (-. /0 / one millionths), nano

second (-./1 & one billionths), and 2ico second (-./-3 / one trillionths) 4ence a computer

#ith speed - microsecond can perform - million instructions in 5ust - second (6or

e7ample in one second this computer can perform the follo#ing tasks

o Calculate the grade point average for 8... students

o Calculate the total value of all books used by students in a university

Accuracy

9o# a days, computers are being used in life/and/death situations (6or e7ample, 5et pilots

rely on computer computations for guidance, 4ospitals rely on patient/monitoring

systems in critical & care units) #hich needs almost hundred percent accuracy 6rom this

#e can understand that computer is accurate and consistent :nless there is an error in the

input data or unreliable program the computer processes its task accurately

Capacity


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!he ability of computers to store and process vast amounts of data continues to gro# A

computer operating at 3.. '4 can move data from one location to another at a rate

e7cess of -3 billion characters (symbols) per second

Durability and reliability

Computers are durable and e7tremely reliable devices !hey can operate error/free over

long periods of time

Dilience

Computer, being a machine, does not suffer from the human traits of tiredness and lack of

concentration If four million calculations have to be performed, then the computer #ill

perform the last four/millionth calculation #ith the same accuracy and speed as the first

calculation

!ersatility

s mathematics

and design computations can also be efficiently used by the company to track inventory,

process payroll, pro5ect earnings, and fulfill all its reporting needs

!oday>s computers are versatile in #hat they can do; computers and their components are

used in applications never before envisioned 6or e7ample; in home appliances (#ashing

machines, ovens) home entertainment centers, traffic lights, automobiles, banking,

assembly plants, space probes, art, music, education, hospitals, and agriculture, to name

fe# !he versatility of the computers and its use in a #ide array of application are limited

only by the imagination of the human mind

"ote: ?ven if the above main characteristics of computers are increasing #ith time, the

cost and sie of computers are decreasing

1.1.#. Application of Computers

Why we use Computers+

!he follo#ing are some of the capability of Computers, #hich are reasons to use

Computers


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tore and process large amount of information #ith high speed and accuracy;

!ransmit information across continents via communication channels;

imulate events;

2erform comple7 mathematical computations and make comparisons;

'onitor ongoing industrial operations;

2erform repetitive processes #ith great ease, speed, and reliability;

!herefore, computers are applicable for any functions or process that reuires these

abilities

!he main areas of computer applications can be listed as follo#s

$earnin Aids

?7ample learning toys, programs range from simple arithmetic to calculus, from

?nglish grammar to creative #riting and foreign language, and from basic graphics to

engineering design models,)

%ntertainment

?7amples Games

Commercial or business applications

Computers are needed to perform business operations that reuire handling large

amounts of data everal computer applications are available to assist business in

#orking #ith large volumes of data

?7amples are

!e7t processing

Accounting and 6inance management

Inventory control

Database management

tatistical analysis

Scientific & enineerin and research applications

Computers are used for scientific research, comple7 mathematical calculations,

design #ork, and analysis and control of physical systems


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?7amples are

pace technology

'eteorological observatory systems

Astronomical investigations

Design of machines and

Control of manufacturing process

'nformation (tilities

Information utilities companies use large computers that store huge amount of

information about many different sub5ects !hese computer systems and their vast

amount of data are available for personal use 6or e7ample information utilities can

allo# a computer user to read the daily ne#s, research published #orks, send a letter to a

friend, play games, make airline reservations, obtain the latest stock market uotations,

and perform many other activities

?7ample Internet

?thiopian airline is a member of *orld/*ide reservation system called Gabriel system

!he main database is located at Atlanta, Georgia

'ore than @ airlines including ?A" share =e7tract=transmit information using

Gabriel

6acilities included

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'odems

%lectronic )an*in and Service:

?7ample

!eller 'achine (customers are issued cards that permit them to use other banks

teller machine>s)

Bnline banking (A bank customer can use his= her computer to check account

balances, transfer funds, pay bills)

Shoppin from +ome

Individual may no# shop by computer in the comfort of their home

+ousehold Control

A gro#ing number of the ne#er houses hold devices are computers controlled

6or e7ample ecurity systems, refrigerators, micro#ave ovens, #ashers, stereos, and

televisions !his computer controlled home security system monitors movements, broken

glass, unla#ful entry #ithout a security code, and so on, and alerts the local police

department

Weather and %nvironment

Computer euipment may sho# temperature ranges, precipitation levels and #ind

flo# and can be used in #eather forecasting Computer can also help in overcomingenvironmental haards

,ransportation

Computers have affected almost every kind of transportation 'any aircraft can

fly under the control of the computer; in this situation, the captain simply serves as a

manger by telling the computer #hat to do In Cars, computers have provided functional

controls such as spark and fuel control

-edical and +ealth Care

Computers have long been used by hospitals for routine record keeping !oday,

ho#ever, many people o#e their lives to the computer Computers are used in hospitals

as sensors (device that detect changes in blood pressure, heart rate, temperature), testing

(scan the body and provide 8/D figure), patient treatment


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outine and Danerous ,as*s

Computers are used in routine tasks And they can perform task in environments

to dangerous for human #orkers

Consultant /%0pert system

An ?7pert system is a computer program, #hich can solve problems from a

specific kno#ledge base !hese systems donEt replace e7pert humans because the

kno#ledge base of e7pert system is given from the skilled specialist

?7ample 'ycin (a medical diagnostic program by using sophisticated decision making

process)

1.#. %volution of Computers

Although computer professionals do not agree on e7act dates or specifics, computer developments are often categoried by generations Actually there are four generations

and ma5or characteristics that distinguish these generations are the follo#ing

Dominant type of electronic circuit elements used

'a5or secondary storage media used

Computer language used

!ypes or characteristic of operating system used

'emory access time (time to store or retrieve a #ord or data from memory)

Computer generations are usually categoried by dramatic improvement in the hard#are,

typically refold or better increases in speed and reliability

2irst eneration /1345s

:sed vacuum tubes as components for the electronic circuit

2unched cards #ere the main source of inputs, and magnetic

grams #ere used for internal storage

Bperate in a speed of milliseconds (thousands of a second)

and could handle more than -.,... additions each second

'ost applications #ere scientific calculations

!hey generate huge amount of heat

!hey solve one problem at a time


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!hey are room/sied and #eights up to 8. tones (8...FG)

!hey need 3..F* of po#er to operate, #hich contains -,... acuum !ubes

Second enerations /early 1365s

!ransistors #ere the main circuit components (!ransistors are a solid statedevice made from silicon #hich is smaller, cheaper, faster, dissipate less

energy and more reliable than vacuum tube but #ork in the same #ay #ith

the vacuum tube)

Invented by

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Computer storage s#itched from magnetic cores to integrated circuit boards that

provide modularity (e7pandable storage) and compatibility (interchangeable

euipment

9e# input=output methods such as optical scanning and plotters

oft#are become more important #ith sophisticated operating systems, improved

programming languages,

Feyboards and 'onitors introduced at this time

2ourth eneration /late 1385s7 early 1393s

Greatly e7panded storage capabilities and improved circuitry

4as "arge/cale Integrated Circuit ("I) #hich has several hundred

thousands of transistors placed on one tiny silicon chip

Computer memory operates at speeds of nano seconds (billionths of a

second) #ith large computers capable of adding - million numbers

per second

,he fifth eneration computer

!his computer generation is still in progress An architecture, #hich makes use

of the changes in technology and allo#s a simple and natural methodology for solving

problems, is being sought !hese computers #ill have intelligent processors ie,

processors #hich can dra# inferences :sers #ill also be able to interact #ith them in

natural languages such as ?nglish, German etc Japans are #orking intensively on the

pro5ect for developing the th generation

Summary of eneration of computers

eneration 1st #nd ;rd

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device

$anuae 'achine assembly 6ortran, CB

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more, the t#o beads above the cross bar are moved back, and an e7tra - (the Cary) is

added to the #ire on the left

!his process can be easily generalied to addition and subtraction of more than t#o

numbers

b =ascal>s Calculator: It is the first true mechanical calculator In

-0@3, at the age of -1, the 6rench philosopher and mathematician s calculator has one #heel corresponding to each po#er of -.; each

#heel has -. position, one for each of the digits (.,1) Although, 2ascal>s calculator

could only add and subtract, it could be used indirectly for multiplication (by

successive addition) and division (by successive subtraction) as #ell

c ,he Difference %nine: It is the forerunner of the modern

computer Charles

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/ Output #as to print or a card punch device

s ,abulatin -achine: 4erman 4ollerith

#as a statistician that in -. and develop his machine commissioned by the :

Census

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,he !on "eumann -achine: !he task of entering and altering

programs for the ?9IAC #as e7tremely tedious on 9eumann #as the consultant on

the ?9IAC pro5ect and for#ard the stored program concept , ie designing the

computer to get its instruction by reading them from memory alongside the data and a

program could be set or altered by setting the values of a portion of a memory

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!hermometer

oltmeter

peedometer

Gasoline pomp & Contains an analog Computer that converts the flo# of pumpedfuel into t#o measurements the price of the delivered gas and the uantity of

pumped fuel

Analog computers are used for scientific and engineering purposes Bne of the

characteristics of these computers is that they give appro7imate results since they deal

#ith uantities that vary continuously

!he main feature of analog computers is that they are very fast in operation as all the

calculations are done in parallel mode It is very easy to get graphical results directly

using analog computer 4o#ever, the accuracy of analog computers is less

ii. Diital Computers

Digital computers deal #ith discrete variables; they operate by counting rather

than measuring :nlike analog computers, they operate directly on numbers (or digits)

that represent numbers, letters, or other special symbols

In digital computers, analog uantities must be converted into digital uantity

before processing

Eamples

Abacus

Desk top pocket computers

!he general purpose computers

Digital computers have higher accuracy and speed than the analog ones

iii. +ybrid Computers

!hese computers incorporated the measuring feature of analog computer and

counting feature of a digital computer 6or computational purposes, these computers usethe analog components and for the storage of intermediate results, digital memories are

used

A hybrid computer processes the information by collecting input data #ith analog

method, converts it into digital uantities, processes the digital values and converts the

output from digital to analog form


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!hese computers are broadly used for scientific applications, various fields of

engineering and industrial control processes

Eample

Intensive Care :nit (IC:) section, in the hospital, uses analog devices to measure the

patient>s heart function, temperature and other vital signs !hese measurements may then

be converted into numbers and supplied to a digital component in the system !his

component is used to monitor the patient>s vital signs and to send an immediate signal to

the nurse>s station if any abnormal readings are detected

!) Classification According to "urpose

Computers can be applied or used for different purposes !hey can be used either for

special purposes or general#purposes$

i. Special =urpose Computers

!hey are designed to solve a single type of problem, that is, their components and

function are uniuely adapted to a specific situation involving specific application

!hese computes cannot be used for other applications unless their circuits are redesigned,

that is, they lacked versatility 4o#ever, being designed for specific tasks, they can

provide the result very uickly and efficiently

Eample !he public telephone bo7

!raffic control system

!icket machines (used in grocery, super market etc)

2ocket calculators etc

Counters

'ost analog computers are special purpose computers

ii. eneralpurpose computers!hey are designed to solve a range of problems through the use of $store program

concept%

!hese machines can be used for various applications, ranging from scientific as

#ell as business purpose applications !hough such computers are versatile and fle7ible,

they generally lack in speed and efficiency


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?7amples

0 'icro computers

0 'ini computers

0 uper computers etc

C) Classification According to %unctionality

At this stage, by a computer, #e mean a general/purpose digital computer

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&icroprocessor is a processor all of #hose components are on a single integrated/

circuit chip ince its C2: is integrated in a single circuit, it can serve only a single user

at a time 'ost of home and personal office computers are microcomputers

'icrocomputers include des'top, laptop, and handheld models such as 2DA

(2ersonal Digital Assistants)

Des'top computers !hey are the most common micro computers !hese micro

computers typically consist of a system unit, a display monitor, a keyboard, internal hard

disk storage, and other peripheral devices

aptop Computers A laptop is a portable computer, that is, a user can carry it

around ince the laptop computer resembles a notebook, they are also kno#n as

noteboo's !he main advantage of this computer is that one can use this computer

any#here and at anytime, especially #hen one is traveling and does not have a proper

place to keep it 'oreover, these computers do not need any e7ternal po#er supply as a

rechargeable battery is completely self/contained by them

andheld Computers A hand/held computer is a computer that can conveniently

be stored in a pocket and used #hile the user is holding it A 2DA user generally uses a

pen or electronic stylus, instead of a keyboard for input ince these computers can be

easily fitted on the palmtop, they are also kno#n as palmtop computers

!he performance and usage of personal computer is relatively increased #ith a

very high rate


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