Chapter 2 The development of computers

1
Chapter 2 The development of computers

• Learning outcomes
• Outline the history of computers
• Explain Von-Neumann Architecture
• Explain the advantage of using the binary system
  in computing and not the decimal one.

2
Additional reading

• Essential
• Stallings (2003) Chapter 2.1
• Further reading
• Brookshear (2003) Chapter 0.2
• Schneider and Gersting (2004) Chapter 1.4

3
Lesson plan

• Introduction
• Definition of a computer
• History of computer machines.
• Hardware and software
• Compilers

4
Introduction

• Modern computers are
• Small,
• Fast,
• Can do different things
• To understand how modern computers work
• It is useful to know their development history
• How is information represented ?
• How is information stored?
• How is information processed?

5
What is a computer?

• Human who performs calculations
• Calculating machine
• General problem solver
• Machine that performs repeated operations
• Machine that can be programmed to perform
  different operations

6
Navigation problem

• Originally, a word computer was assigned to
  humans who were employed to solve difficult
  equations such as computing tabulated values that
  could be used by navigators.
• Humans implies mistakes.
• Large fortune can lost.

7
A computer is something that does arithmetic sums

• Charles Babbage (mathematician) realised that a
  fortune can be saved if the production of these
  tables can mechanised.
• There were a limited mechanic machines at that
  time
• such as abacus (limited in its precision)
• A Computer becomes
• Something that does arithmetic sums.

8
A computer is something that can perform repeated
operations.

• In 1822 C. Babbage proposed
• A mechanical calculating device designed to
  repeatedly add large number.
• A computer becomes
• something that can perform repeated operations
  without error.

9
A computer is machine that can perform different
tasks

• 1833
• C. Babbage designed a machine that could perform
  different operations. Order of operation can be
  changed after.
• A computer becomes
• A machine that can be programmed to perform
  different tasks.

10
First programmer?

• Lady Ada Lovelace
• She met C. Babbage in 1833
• She then wrote a program for his machine.
• She was the worlds first programmer ?
• More about Ada Lovelace go to http//www.exeter.ac
  .uk/BABBAGE/ada.html

11
Origin the word Algorithm?

• The idea of a program or algorithm
• was already known at that time.
• The idea of Algorithm was introduced by
• Muhammad Ibn Mussa AlKhowarizmi since 12th
  century.
• The word algorithm originated from Alkhowarism

12
Abacus machine (1)

• First computer Abacus

A rack with a sliding beads.
13
Abacus machine (2)

• Emerged about 5,000 years ago in China.
• Not an automated computer
• Allows users to perform computations using a
  system of sliding beads arranged in a rack.
• Only helps the remember the current state of
  calculation.

14
Pascals System Gear Blaise Pascal(1623-1662)

• It was developed by Blaise Pascal in 1642.
• If is also known as
• Pascal mechanical calculator
• Pascaline
• Pascals adder.
• It is an 8 figure calculating machine
• adding,
• subtracting, and
• carrying 10's, 100's, and 1000's
• Limitations addition and subtraction only.

15
Pascals System Gear
8 movable dials

• Uses a base of 10
• add sums up 8 figures.
• When the10s dial moves one revolution, the
  100s dial moves one notch.

16
Gottfried Von Leibniz

• Leibniz developed Pascals ideas.
• In 1671, he introduced a new device called Step
  Reckoner.
• The device can performs the followings
• Addition and subtraction
• multiplication and division.
• Evaluation of square roots by series of stepped
  additions.

17
Babbages Difference Engine Charles
Babbage(1791-1871)

• It could compute tables of numbers for naval
  navigation, e.g. x2 for any value of x. This
  machine punched the result into a copper plate.
• For more information about Babbages work go to
  http//www.maxmon.com/1830ad.htm
• http//en.wikipedia.org/wiki/Charles_Babbage

18
Electronic Numerical Integrator and Computer
(ENIAC)

• (1943-1946) by John Mauchly
• ENIAC used vacuum tubes for number computation.
• The switches between the vacuum tubes were able
  to represent 2 states ON and OFF.
• However, programming was done manually.

19
17,468 vacuum tubes 70,000 resistor 6,000 manual
switches 30 tones weight Covers 167 square
metres 160 kilowatts of electric power
20
Von Neumann Machine

• Invented in 1943 by John Von Neumann
• First machine that could perform all operations
  electronically.
• No manual switching between states is needed
• It consists of
• A central processing unit
• Memory as well as Input/Output devices
• These were connected through a system bus (set of
  wires)

21
Von Neumann architecture
Main memory
CPU
Add. bus
Data bus
Control bus
22
Industry Standard Architecture ISA Binary
System

• John von Neumanns architecture was also referred
  to as ISA machine
• The ISA used vacuum tubes that were based on the
  binary system.
• The invention of transistors in 1947
  (semi-conductor with 2 states) favoured the
  binary system to the decimal one.

23
Computers since the 1940s

• 1st generation (1943-59) Bulky machines using
  vacuum tubes.
• 2nd generation (1959-65) Transistor-based
  machines with magnetic core memory, programmed
  with high level languages (e.g. Fortran or
  Cobol).
• 3rd generation (1965-75) Integrated circuits.
  Operating systems permitting shared use of
  machines.
• 4th generation (1975-85) Machines built with
  large-scale and very large-scale integrated
  circuits (VLSI), e.g. Microcomputers. Graphical
  User Interfaces (GUIs), networks
• 5th generation (1985-present) Multimedia
  interfaces, mobile computing, parallel
  processing. Most of todays computers also
  inherit the properties of 4th generation devices.
  

24
Hardware and Software

• Hardware
• the physical components of a machine.
• Touchable
• Software
• Instructions performed by a computer
• Sequence of instructions that include
• Conditional statements
• Block of statements that are to be repeated

25
Software Terminology

• Program
• Set of instructions or rules that a computer can
  apply
• Software consists of a set of programs
• Application program
• An end-user employs, such word processor, web
  browser, etc..
• System programs
• Manages the running of applications, such as
  operating system.
• Link between the application software and the
  hardware

26
Compilers

• Executable/Object Code
• It is expressed in machine code.
• A language the machine hardware can understand
• Source Code
• The text of a program written in high-level
  language.
• Compiler
• Translates from source code to object code,
  machine code.

27
Basic Process of Compilation
28
Files and directories

• A file is collection of data (e.g. plain text
  document)
• Directories
• A means of organizing files
• Usually form a hierarchy
• Root
• is the top directory in the hierarchy
• (/ Unix and \ in Ms-dos).

29
Computer Component

• Most computers consist of
• Input/output devices keyboard, mouse
• Visual display units screen
• Graphical user interfaces display on the screen
  that allows you to interact, e.g. by pointing,
  clicking, dragging. Objects that you see on
  screen, e.g. wastebasket, folders, symbols such
  as disk, scissors, etc.
• CPU processor (e.g. INTEL, ) made out of
  silicon
• Hard-drive (magnetic disk, now more than a
  Terabyte)
• RAM (working memory, now more than a Gigabyte)
• Cards, such as graphic cards, sound cards,
  Ethernet cards
• Operating systems, e.g. UNIX, Linux, Windows,
  etc
• Programmes (written in assembly language, Java,
  C, C, Visual Basic, Python, Perl etc.)