Lecture 3

Introduction to Information and
Communication Technologies
Abdul Qadeer
Department of Information technology
GCUF Main Campus
The slides are adapted from the publisher’s material
Computer Science Illuminated
6th Edition
Goals and Objective
• Describe the layers of a computer system
• Describe the concept of abstraction and its
relationship to computing
• Describe the history of computer hardware and
software
• Describe the changing role of the computer user
• Distinguish between systems programmers and
applications programmers
Computing Systems
Hardware The physical elements of a

computing system (printer, circuit boards,
wires, keyboard…)
Software The programs that provide the

instructions for a computer to execute
Layers of a Computing System
INFORMATION LAYER
•Information inside a computer is represented
in the form of binary digits, 1 and 0.
•To understand how computers process
information, we must understand the binary
number system and its relationship to other
number systems.
•All types of information, text, numbers,
images, audio, and video, have to be
represented in the computer using specific
methods.
HARDWARE LAYER:
•Hardware refers to physical components of the
computer.
•Computer circuitry is mainly built of transistors.
They act like switches and control the flow of
electrical states in the computer.
•These transistors are used to make gates and
eventually the computer's main components like
the central processing unit and memory.
PROGRAMMING LAYER
•At the hardware layer, the computer needs to
be programmed in machine and assembly
language.
•Assembly language uses words and symbols
to give instructions to the computer.
•Instructions in assembly are translated to
machine language by a program called an
Assembler.
OPERATING SYSTEM LAYER
•This layer in computing uses a software that
manages system resources.
•Resources are processor, memory, and I/O
devices.
•Operating system combined with software
that makes use of resources is called system
software.
•Common Operating systems are Windows,
MacOS, Linux, etc.
APPLICATION LAYER
•This is where the user interacts with the
computing system using an application
software.
•Application software is used for solving real-
world problems.
•These software can be used to design real-
world objects, play games, solve problems of a
specific field, etc.
•Almost every area of computer technology
uses specific application software to make use
of computers.
COMMUNICATION LAYER
•Computers are mostly used in today's world
for communication.
•Computers for this purpose are connected to
networks.
•Internet is the result of advancement in the
computer communication technology.
•Today, World Wide Web uses the internet to
provide access to all kinds of information. It
has given birth to new entertainment industries
as well.
Abstraction
Abstraction A mental model that removes

complex details
Internal and Abstract View
12
History of Computers
Early History of Computing
Abacus
An early device to record
numeric values
Blaise Pascal
Mechanical device to add, subtract
Joseph Jacquard
Jacquard’s Loom, the punched card
Charles Babbage
Analytical Engine
Early History of Computing
Ada Lovelace
First Programmer, the loop
Harvard Mark I, ENIAC, UNIVAC I

Early computers launch new era in mathematics, physics,
engineering and economics
First Generation Hardware (1951-
1959)
Vacuum Tubes
Large, not very reliable, generated a lot of heat
Magnetic Drum
Memory device that rotated under a read/write head
Card Readers  Magnetic Tape Drives

external memory
Second Generation Hardware (1959-
1965)
Transistor
Replaced vacuum tube, fast, small,
durable, cheap
Magnetic Cores
Replaced magnetic drums, information available
instantly
Magnetic Disks
Replaced magnetic tape, data can be accessed directly
Third Generation Hardware (1965-
1971)
Integrated Circuits
Replaced circuit boards, smaller, cheaper, faster, more
reliable
Transistors
Now used for memory construction
Terminal
An input/output device with a keyboard and screen
Fourth Generation
Hardware(1971-?)
Large-scale Integration
Great advances in chip technology
PCs, the Commercial Market, Workstations

Personal Computers and Workstations emerge
New companies emerge: Apple, Sun, Dell …
Laptops, Tablet Computers, and Smart

Phones
Everyone has his/her own portable computer
Parallel Computing and
Networking
Parallel Computing
Computers rely on interconnected central processing
and/or memory units that increase processing speed
Networking
Ethernet connects small computers to share resources
File servers connect PCs in the late 1980s
ARPANET and LANs  Internet

First Generation Software (1951-
1959)
Machine Language
Computer programs written in binary (1s and 0s)
Assembly Languages and Translators

Programs written using mnemonics, which were
translated into machine language
Programmer Changes
Programmers divide into two groups: application
programmers and systems programmers
Assembly/Machine
Second Generation Software
(1959-1965)
High-level Languages
English-like statements made programming easier:
Fortran, COBOL, Lisp
Third Generation Software (1965-
1971)
Systems Software
Utility programs
Language translators
Operating system, which decides which programs
to run and when
Separation between Users and Hardware

Computer programmers write programs to be used by general
public (i.e., nonprogrammers)
Third Generation Software
(1965-1971)
Fourth Generation Software (1971-
1989)
Structured Programming
Pascal
C++
New Application Software for Users

Spreadsheets
Word processors
Database management systems
Fifth Generation Software (1990-
present)
Microsoft
Windows operating system and other Microsoft application
programs dominate the market
Object-Oriented Design
Based on a hierarchy of data objects (i.e. Java)
World Wide Web

Allows easy global communication through the Internet
New Users
Today’s user needs no computer knowledge
Do you know?
Who said the Analytical Engine “weaves algebraic patterns”?

Ada Lovelace
Where did scientists build the first nanotube computer?
Stanford University.
What computer company was launched in a garage?
Hp , Apple
What companies turned Jobs and Wozniak away?
HP
Where is the Computer History Museum?
USA
What is Room to Read?
A non profit organization for improving literacy and gender equality in education
When and where were the first CS Departments formed?
The first CS department was formed in US at Perdue University In October 1962

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Introduction to Information and

Hardware The physical elements of a

Software The programs that provide the

Abstraction A mental model that removes

Harvard Mark I, ENIAC, UNIVAC I

Card Readers  Magnetic Tape Drives

PCs, the Commercial Market, Workstations

Laptops, Tablet Computers, and Smart

ARPANET and LANs  Internet

Assembly Languages and Translators

Separation between Users and Hardware

New Application Software for Users

World Wide Web

Who said the Analytical Engine “weaves algebraic patterns”?

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