1. PHAS151 – COMPUTER LITERACY I
BRIEF HISTORY OF COMPUTERS

2. BRIEF HISTORY OF COMPUTERS Definition
What is a Computer? Some Popular Definitions. 1.
A device that
accepts data
then performs arithmetic or logic operations
that manipulate or change the data and finally
produces new results ( information) from the data.
(by Rochester – Computers)

3. Definition 2. a machine that can be programmed to accept data (input),
process it into useful information (output),
and store it away ( in a secondary storage device) for safe keeping or later use.
The processing is directed by the software, but performed by the hardware.
By – Capron and Perron : Computers and Information Systems

4. Definition
3. A machine which inputs, processes and outputs data under the control of a stored program. by Longman Revise Guides : Computer Science

5. Definition
4. is a device that works under the control of stored programs, automatically accepting, storing and processing data to produce information that is the result of that processing.

6. BRIEF HISTORY OF COMPUTERS The Basic Functions of a Computer
So, when the computer processes data it actually performs a number of separate functions as follows:
INPUT: the computer accepts data from outside for processing within.
Storage: the computer holds data internally before, during and after processing.
Processing: the computer performs operations on the data it holds.
Output: the computer produces data from within for external use

7. BRIEF HISTORY OF COMPUTERS COMPUTER GENERATIONS
ALL current computers are built to the basic Design postulated by John von Neumann and known as Von Neumann Machines The detailed design of which has now reached five Generations

8. Block Diagram of Von Neumann System
INPUT
PROCESS
OUTPUT
PRIMARY MEMORY
SECONDARY MEMORY

9. The key elements in the system
Input
Process
Output
Store

10. COMPUTER GENERATIONS First
Dating from about 1945
Technology : based on valve technology and used magnetic core memory.
Speed : much faster than the earlier electromechanical machines, but were most unreliable
Consumed vast amounts of electrical power
Took up a huge amount of physical space

11. COMPUTER GENERATIONS First
Needed engineers employed by the manufacturer to be resident on site
Memory was slow and cost a great deal
No large scale file store, used drums + tapes (no disk storage)
MAINFRAMES = Monsters

12. COMPUTER GENERATIONS Second
Invented around 1949
Technology: Use of transistor technology i.e. replacement of valves
Reduced size and power requirements
Increase reliability though memory was still quite large and expensive e.g. UNIVAC I
It was, for the first time, possible to buy a computer

13. COMPUTER GENERATIONS Third
Dating from about 1965
Technology : used Integrated Circuits( IC) or Small Scale Integration (SSI)
Used the first Silicon circuits
Further reduction in size and much less heat output
Evolution of semi-conductor memory helped reduced the cost of memory.
No more special air-conditioned rooms
Evolution of the minicomputer

14. COMPUTER GENERATIONS Fourth
Dating from 1970s
Technology: extended use of ICs to Large Scale Integration (LSI) and Very Large Scale Integration (VLSI)
Considerable reduction in Size hence ‘computer on a chip’ technology
This further Miniaturization resulted in the development of the microprocessor
Home computers

15. COMPUTER GENERATIONS Fifth
Dating from 1980s
VVLSI
Further miniaturization
Involve Ultra fast and powerful computers
Features : parallel architecture and data a flow rather than instruction flow philosophy.

16. TYPES OF COMPUTERS
Classification in the early days of the Industry was based on: computers designed for business applications e.g. IBM 1400 series computers designed for scientific applications e.g. IBM 7090 series

17. TYPES OF COMPUTERS
MAINFRAME
MINICOMPUTER
MICROCOMPUTER
SUPERCOMPUTER

18. TYPES OF COMPUTERS MAINFRAME
The very first type
Very expensive in terms of cost
Memory often organised in words of 64+ bits
Capacity of memory very high and at the top end compared to that of other computers
Often dedicated to multi-access applications
Peripherals tended to be smaller computers and remote
Have many processors (multiprocessor)
Efficiently organised for unlimited upward expansion

19. TYPES OF COMPUTERS MINICOMPUTERS
Designed sometime later than the mainframe, 1970s
Small in physical size ( compared to mainframe)
Cheaper than the available Mainframes
Memory organised in words of bits
Use cheaper, and perhaps slower peripherals
Have limited upward expansion
Often dedicated to a single application or range of applications rather than being ‘general purpose’

20. TYPES OF COMPUTERS MICROCOMPUTERS
The starting point is the term
MICROPROCESSOR
May be defined as
a computer processor on a silicon chip
which has
circuits imprinted on a small wafer of silicon.

21. TYPES OF COMPUTERS MICROCOMPUTERS
Note in some cases the whole computer can be on a silicon chip hence the expression MICROCOMPUTER

22. TYPES OF COMPUTERS MICROCOMPUTERS
It is more usual for the main processor to be on a single chip mounted on a circuit board with one chip containing the Control Unit ( CU ) and Arithmetic Logic Unit (ALU) and additional chips for the working storage/ memory and for the control of data flow to and from the peripherals

23. TYPES OF COMPUTERS MICROCOMPUTERS
Is most easily defined as
a computer which uses a microprocessor as its Central Processing Unit (CPU).
Office microcomputers are called Personal Computers (PCs) and the top of the range models are referred to as Workstations.
e.g. SUN, APOLLO systems

24. TYPES OF COMPUTERS MICROCOMPUTERS
Aspects of Microcomputers
Quite small in physical size compared to its predecessors – mainframe, minicomputers
Portable machines
Are becoming smaller yet more powerful
They are machines dedicated to single-access (personal) applications
The price is far less than that of its predecessors – affordable by the individual

25. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Desktop Unit – flat based system unit
Tower Unit
Laptops/Notebooks
Subnotebooks
Personal Digital Assistants
Microcomputer and Networks
Servers
Microcontrollers

26. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Desktop Unit – flat based system unit
are small computers with system units that can fit next to a desk, on a desk, or can be carried around

27. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Tower Unit – tall system unit
have system units that are higher than they are wide and can be placed on the floor

28. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Laptops / Notebooks
This is a portable PC, may be either AC-powered, battery-powered, or both.
these computers are ideal for users who have to work away from home – combines the power of PC with mobility.

29. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Subnotebooks
are smaller notebooks with
less display/monitor and keyboard capabilities to enable less weight
they typically have an external floppy disk drive

30. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Personal Digital Assistants ( PDAs )
are much smaller that the subnotebooks
they combine
pen input
writing recognition
personal organizational tools and
communication capabilities in a very small package.
e.g. Palmtops , Electronic Organizers

31. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Microcomputers and Networks
PCs are now found in most businesses
Use
either as
Standalone machines
Connected to a Network
such as Local Area Network ( LAN )
connects, usually by a special cable, a group of PCs and peripheral devices in an office or a building.

32. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Microcomputers and Networks
Server
In most LANs, one PC is assigned the role of server
meaning that it stores data and software for use by the other PCs and/or performs services for them , such as printing

33. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Microcontrollers
also called embedded
dedicated
hidden computers
they are tiny computers installed in
‘smart’ or ‘intelligent’ appliances

34. TYPES OF COMPUTERS MICROCOMPUTERS
Kinds of Personal Computers ( PCs)
Microcontrollers
like
pocket calculators
microwave oven
traffic light
radios
mobile phones
they are dedicated performing a restricted number of tasks

35. TYPES OF COMPUTERS SUPERCOMPUTERS
These are machines produced with the following philosophy
the machine must run as fast as possible
the capacity must be as great as possible
peripherals should be as fast as possible, consistent with maximum capacity available
there is little or no restriction on price, i.e. money is no object.

36. TYPES OF COMPUTERS SUPERCOMPUTERS
Aspects
First developed in the 1970s
The fastest and highest-capacity computers
Used for research
Have hundreds to thousands of processors

37. TYPES OF COMPUTERS SUPERCOMPUTERS
Examples
CRAY
OPTION RED
have small but significant market, particularly in the area of number crunching i.e. processing large volumes of numeric data.

38. CAPABILITIES OF COMPUTERS
Characteristics of computers that make them so useful
speed
accuracy
reliability
storage capability
productivity
decision-making
cost reduction

39. CAPABILITIES OF COMPUTERS
Speed
basically the processor speed performing millions and millions of instructions/operations in
nanoseconds /100,000,000 seconds
microseconds 1/1,000,000 seconds

40. CAPABILITIES OF COMPUTERS
Accuracy
provide the microprocessor with the correct instructions
then planned operations can be repeated millions of times without a single error
Garbage In Garbage Out ( GIGO) concept applies
errors can occur
make errors only when there is a breakdown in the computing system

41. CAPABILITIES OF COMPUTERS
Storage capability
can store tremendous amounts of data
efficiently sorting, finding, and retrieving at lightning speed
advantage:
the capability to store volumes of data is especially important in an information age

42. CAPABILITIES OF COMPUTERS
Emergent capabilities
the above three
speed
accuracy
storage capability
are fundamental capabilities of computers
by-products of computers

43. CAPABILITIES OF COMPUTERS
Productivity
can increase productivity

44. CAPABILITIES OF COMPUTERS
Decision-making
Complex situations
Using problem-solving techniques
Sort things out
Do analyses
Make choices

45. CAPABILITIES OF COMPUTERS
Cost Reduction
because it improves productivity and aids decision-making ,
the computer helps to
eliminate wasteful practices
hold down the cost of labour, energy and paper work