PHAS151 – COMPUTER LITERACY I BRIEF HISTORY OF COMPUTERS

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)

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

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

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.

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

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

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

The key elements in the system Input Process Output Store

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

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

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

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

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

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.

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

TYPES OF COMPUTERS MAINFRAME MINICOMPUTER MICROCOMPUTER SUPERCOMPUTER

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

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 16-24 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’

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.

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

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

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

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

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

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

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

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.

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

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

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.

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

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

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

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.

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

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.

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

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

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

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

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

CAPABILITIES OF COMPUTERS Productivity can increase productivity

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

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