Introduction to Computing: An Overview

Course: Introduction to computing.
Module 1:
Overview of Computer Science.
Islamic Online University

Objectives
• Obtain an overview of computer science
• Become familiar with the definition of computer, its history and the
various classifications of computers.
• Learn about the various types of computers

Content.
1. Definition of computers
2. History of computers
3. Classifications of computers
1. By function
2. By purpose
3. By capabilities.

Definition of computers.
• An electronic device which is capable of receiving information (data) in
a particular form and of performing a sequence of operations in
accordance with a predetermined but variable set of procedural
instructions (program) to produce a result in the form of information or
signals..
• Data is a collection of facts, such as numbers, words, measurements,
observations or even just descriptions of things.
• Data can be qualitative or quantitative.

Definition of computers.
DATA
Qualitative
Quantitative
Is descriptive information
(it describes something). For
example “I Love Computer”
Is numeric
information
(numbers)
Discrete
Continuous
can only take certain
values (like whole
numbers). For
example 10
can take any value
(within a range). For
example 23.45678
• A computer can also be defined in terms of functions, it’s a device that can:
• Accept data
• Store data
• Process data
• Retrieve data
• Print data

History of Computers.
• The word ‘computer’ is an old word that has changed its meaning several times in the
last few centuries. Originating from the Latin, by the mid-17th century it meant
‘someone who computes’.
• The American Heritage Dictionary (1980) gives its first computer definition as “a
person who computes.”
• The term ‘history’ means past events. The encyclopedia Britannica (2003) defines it
as “the discipline that studies the chronological record of events (as affecting a nation
or people), based on a critical examination of source materials and usually presenting
an explanation of their causes.”

The Early Period: Up to 1940
• Seventeenth century: automation/simplification of arithmetic for scientific research
• John Napier invented logarithms as a way to simplify difficult mathematical
computations (1614)
• The first slide rule appeared around 1622
• Blaise Pascal designed and built a mechanical calculator named the Pascaline
(1672)
• Gottfried Leibnitz constructed a mechanical calculator called Leibnitz’s Wheel
(1674)

The Early Period: Up to 1940

The Early Period: Up to 1940 (Continued)
• Seventeenth century devices
• Could represent numbers
• Could perform arithmetic operations on numbers
• Did not have a memory to store information
• Were not programmable (a user could not provide a sequence of actions to be
executed by the device)

• Nineteenth century devices
• Joseph Jacquard designed an automated loom that used punched cards to create
patterns (1801)
• Herman Hollerith (1880s on)
• Designed programmable card-processing machines to read, tally, and sort
data on punched cards for the U.S. Census Bureau
• Founded company that became IBM in 1924
• Computer Tabulating Recording Company -> IBM

• Charles Babbage
• Difference Engine designed and built in 1823
• Could do addition, subtraction, multiplication, and division to six significant
digits
• Could solve polynomial equations and other complex mathematical problems
• Analytical Engine, designed but never built
• Mechanical, programmable machine similar to a modern computer

• Babbage’s Term Modern Terminology
• mill arithmetic/logic unit
• store memory
• operator processor
• output unit input/output
• Ada Augusta Byron – First programmer

• Nineteenth century devices
• Were mechanical, not electrical
• Had many features of modern computers:
• Representation of numbers or other data
• Operations to manipulate the data
• Memory to store values in a machine-readable form
• Programmable: sequences of instructions could be pre-designed for complex
operations

The Birth of Computers: 1940–1950
• ABC system (Atanasoff-Berry Computer) (1942)
• Mark I (1944)
• Electromechanical computer used a mix of relays, magnets, and gears to process
and store data (binary, memory 72, * 4 s )
• Colossus (1943)
• General-purpose computer built by Alan Turing for British Enigma project -
German Enigma code
• ENIAC (Electronic Numerical Integrator and Calculator) (1946) - Eckert and
Mauchly
• First publicly known fully electronic computer
• Firing tables, 18k tubes, 100X10’, 30 ton, * 4 ms)

The Birth of Computers: 1940–1950

The Birth of Computers: 1940–1950 (Continued)
• John Von Neumann
• Proposed a radically different computer design based on a model called the
stored program computer
• Research group at the University of Pennsylvania built one of the first stored
program computers, called EDVAC (Electronic Discrete Variable Automatic
Computer), in 1951
• UNIVAC-1 (UNIVersal Automatic Computer), a version of EDVAC, first
commercially-sold computer.
• Virtually all modern computers use the Von Neumann architecture

The Modern Era: 1950 to the Present.
• First generation of computing (1950-1957)
• Similar to EDVAC
• Vacuum tubes for processing and storage
• Large, expensive, and delicate
• Required trained users and special environments
• Second generation (1957–1965)
• Transistors and magnetic cores instead of vacuum tubes
• Era of FORTRAN and COBOL: high-level programming languages
• The occupation called programmer was born.

• Third generation (1965 to 1975)
• Era of the integrated circuit
• Birth of the first minicomputer: desk-sized, not room-sized computers – PDP-1
(Programmed Data Processor) (DEC Corp) – Digital Electronic Corporation.
• Birth of the software industry
• Fourth generation (1975 to 1985)
• The first microcomputers: desktop machines (Altair 8800 – 1975)
• Development of widespread computer networks
• Electronic mail, graphical user interfaces, and embedded systems

• Fifth generation (1985–?)
• Massively parallel processors capable of quadrillions (1015) of computations per
second
• Non-Von-Neuman Architectures
• Handheld digital devices
• Powerful multimedia user interfaces incorporating sound, voice recognition,
images, video, television
• Wireless communications
• Massive storage devices
• Ubiquitous computing

Classifications of Computers.
Computers
By Function
Digital
Analog
Hybrid
By Purpose
General purpose
Special purpose
By Capabilities
Micro-Computer
Mini-Computer
Mainframe
Super-Computer

By Function – Digital Computer
• A Digital computer works with data in term of discrete number or digit. These number are
used to perform, arithmetic calculations and also make logical decision to reach a conclusion
depending on the data they receive from the user. All the expressions are coded into binary
digits (0 and 1) inside the computer and it manipulates them at very fast speed.
• A digital computer manipulates data according to the instructions or program given to it in a
certain computer language.
• The instructions and data are fed to the computer in the form of discrete electrical signals.
Digital Computers are easy to program and are in general purpose use. Almost all personal
computers (PCs) belong to this category.

By Function – Analog Computer
• Analog computers actually is a measuring device.
• An analog computer measures continues type of data and use a physical quantity,
such as electric current, speed, weight etc.
• Analog Computers are the first Computers being developed & provide the base for
the development of modern digital computers.
• These computers are mainly made of electrical devices like resisters, amplifiers &
transistors.

By Function – Analog Computer
• This machine has a very limited memory & can perform only certain type of
calculations, which make it specialized machine, suitable for engineering &
scientific calculations.
• In general, Analog computer are very fast in processing because all the operations
performed in this machine are parallel but accuracy of these machines is quite low.
Speedometer and millimeter (used in vehicles), Electric meter & Gas meter (fixed on
the supply line of the house) pressure gauges & thermometers are the general
example of the analog devices.

By Function – Hybrid Computer
• A Hybrid computer is, which combines the analog & digital capabilities in the same
computer system.
• Hybrid computers help the user to exploit the machine's ability to process both
continuous and discrete data. These machines are generally used for scientific
applications & it is also used as a controlling device in an industrial process.
• The results can be obtained either as analog signal or discrete signal e.g., either as
continuous output in the form of graph discreet digits. This result can be obtained
by an electronic device ‘MODEM’. A modem is a device which can transform analog
signals to digital signals and vice versa.

By Purpose– General Purpose
• General Purpose: These computer are designed to solve wide variety of problems
from different fields.
• The hardware and the software of such system are adaptable totally different
environments.
• These Computer are used for different purpose like
• Inventory Control
• Record keeping
• Accounting, payroll etc.

By Purpose– Special Purpose
• Special Purpose: As the name suggests these computers system are used only for
specific purposes or application.
• These special purpose computer system may be defined as a stored programme
computer, whose architecture is oriented towards one or more specific applications.
• These computers handle a very narrow categories of data processing activities. Some
example of special purpose computer with their area of application are as fallows.

By Purpose– Special Purpose
• Special Purpose: As the name suggests these computers system are used only for
specific purposes or application.
• These special purpose computer system may be defined as a stored programme
computer, whose architecture is oriented towards one or more specific applications.
• These computers handle a very narrow categories of data processing activities. Some
example of special purpose computer with their area of application are as fallows.
• Computer used for Process Control in an industry.
• Bio-medical X-ray instrument used only for X-ray.
• ECG machine which is used for ECG test
• CCG machine which is used for CCG test
• Electronic digital blood pressure instrument
• Computer used for air-traffic control.
• Computer system which is used in Robots

By Capabilities – Micro-computer
• These are the smallest range of computers. They were introduced in the early 70’s
having less storing space and processing speed.
• Micro computers of todays are equivalent to the mini computers of yesterday in terms
of performing and processing.
• They are also called “computer of a chip” because its entire circuitry is contained in
one tiny chip. The micro computers have a wide range of applications including uses
as portable computer that can be plugged into any wall.

By Capabilities – Mini-computer
• Mini computers are smaller than mainframes, both in size and other facilities such as
speed, storage capacity and other services.
• They are versatile that they can be fitted where ever they are needed. Their speeds are
rated between one and fifty million instructions per second (MIPS).
• They have primary storage in hundred to three hundred megabytes range with direct
access storage device.

By Capabilities – Super-computer
• Large scientific and research laboratories as well as the government organizations
have extra ordinary demand for processing data which required tremendous
processing speed, memory and other services which may not be provided with any
other category to meet their needs.
• Therefore very large computers used are called Super Computers. These computers
are extremely expensive and the speed is measured in billions of instructions per
seconds.

By Capabilities – Mainframe computer
• These are the largest of computer systems
(not necessarily the fastest or most powerful)-
they certainly will not fit on the top of your
desk.
• It is common to have hundreds of
simultaneous users on such a system. There is
usually a vast amount of RAM, and any extra
peripherals such as tape & disk machines.

Comparisons
Component
Micro-
computer
Mini-
computer
Mainframe
Super-
computer
Main
memory
64,000-7,000,000
characters
1,000,000-
50,000,000
characters
32,000,000-
200,000,000
characters
64,000,000-
2,000,000,000
characters
Storage
capacity
64,000-16,000,000
characters
4,000,000-
64,000,000
characters
32,000.000+
characters
No limitation
Processing
speed
60-1,000,000
instructions
per second
1-5 mips
5 mips
and up
10 mips
and up
Cost $200-$15,000
$10,000-
$475,000
$250,000-
$10,000,000
$10,000,000-
$20,000,000

Benefits of computers to the society.
• Data and information are organized in a better way that makes it easy for retrieval.
• Tasks and activities are automated, thus making jobs easier to execute.
• Brings about faster ways to solve complex human problem.
• Aids human decision making and projections more accurate.
• Helps to solve complex human medical problems.

Summary.
In this module we learnt the following:
• That computer is an electronic device that accepts data, process it and display the
desired output. WYSIWYG
• About the history of computers staring from early period to 1940.
• The birth of ENIAC (Electronic Numerical Integrator and Calculator) (1946)
• The John Von Neumann computer – 1940 -1950
• The modern era of computer – 1st, 2nd, 3rd , 4th and 5th generation.
• The various classifications of computer.
• Benefits of computer to the society.

Introduction to Computing: An Overview

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