BRIEF HISTORY OF COMPUTERS PHAS151 – COMPUTER LITERACY I.
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Transcript of BRIEF HISTORY OF COMPUTERS PHAS151 – COMPUTER LITERACY I.
BRIEF HISTORY OF COMPUTERS
PHAS151 – COMPUTER LITERACY I
BRIEF HISTORY OF COMPUTERSDefinition
What is a Computer? Some Popular Definitions.1.A device that
accepts datathen performs arithmetic or logic operationsthat manipulate or change the data and
finallyproduces 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 COMPUTERSThe Basic Functions of a Computer
So, when the computer processes data it actually performs a number of separate functions as follows:
1. INPUT: the computer accepts data from outside for processing within.
2. Storage: the computer holds data internally before, during and after processing.
3. Processing: the computer performs operations on the data it holds.
4. Output: the computer produces data from within for external use
BRIEF HISTORY OF COMPUTERSCOMPUTER GENERATIONS
ALL current computers are built to the basic Design postulated byJohn von Neumann and known as
Von Neumann MachinesThe detailed design of which has now reached
five Generations
Block Diagram of Von Neumann System
INPUT PROCESS OUTPU
T
PRIMARY MEMORY
SECONDARY MEMORY
The key elements in the system
Input
Process
Output
Store
COMPUTER GENERATIONSFirst
Dating from about 1945Technology : 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 powerTook up a huge amount of physical space
COMPUTER GENERATIONSFirst
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 GENERATIONSSecond
Invented around 1949Technology: Use of transistor technology i.e.
replacement of valvesReduced size and power requirementsIncrease reliability though memory was still
quite large and expensive e.g. UNIVAC IIt was, for the first time, possible to buy a
computer
COMPUTER GENERATIONSThird
Dating from about 1965Technology : used Integrated Circuits( IC) or
Small Scale Integration (SSI)Used the first Silicon circuitsFurther reduction in size and much less heat
outputEvolution of semi-conductor memory helped
reduced the cost of memory.No more special air-conditioned roomsEvolution of the minicomputer
COMPUTER GENERATIONSFourth
Dating from 1970sTechnology: 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 GENERATIONSFifth
Dating from 1980sVVLSIFurther miniaturizationInvolve Ultra fast and powerful computersFeatures : 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 COMPUTERSMAINFRAME
The very first typeVery expensive in terms of costMemory often organised in words of 64+ bitsCapacity of memory very high and at the top end
compared to that of other computersOften dedicated to multi-access applicationsPeripherals tended to be smaller computers and
remoteHave many processors (multiprocessor)Efficiently organised for unlimited upward
expansion
TYPES OF COMPUTERSMINICOMPUTERS
Designed sometime later than the mainframe, 1970s
Small in physical size ( compared to mainframe)
Cheaper than the available MainframesMemory organised in words of 16-24 bitsUse cheaper, and perhaps slower peripheralsHave limited upward expansionOften dedicated to a single application or
range of applications rather than being ‘general purpose’
TYPES OF COMPUTERSMICROCOMPUTERS
The starting point is the term
MICROPROCESSORMay be defined as
a computer processor on a silicon chipwhich has
circuits imprinted on a small wafer of silicon.
TYPES OF COMPUTERSMICROCOMPUTERS
Notein some cases the whole computer can be on a silicon chiphence the expression
MICROCOMPUTER
TYPES OF COMPUTERSMICROCOMPUTERS
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)
andadditional chips for
the working storage/ memoryand for the control of data flow to and from
the peripherals
TYPES OF COMPUTERSMICROCOMPUTERS
MICROCOMPUTERIs 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 COMPUTERSMICROCOMPUTERS
Aspects of MicrocomputersQuite small in physical size compared to its
predecessors – mainframe, minicomputers
Portable machinesAre becoming smaller yet more powerfulThey are machines dedicated to single-access
(personal) applicationsThe price is far less than that of its
predecessors – affordable by the individual
TYPES OF COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Desktop Unit – flat based system unitTower UnitLaptops/NotebooksSubnotebooksPersonal Digital AssistantsMicrocomputer and NetworksServersMicrocontrollers
TYPES OF COMPUTERSMICROCOMPUTERS
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 COMPUTERSMICROCOMPUTERS
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 COMPUTERSMICROCOMPUTERS
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 COMPUTERSMICROCOMPUTERS
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 COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Personal Digital Assistants ( PDAs )
are much smaller that the subnotebooksthey combine
pen input writing recognition personal organizational tools and communication capabilities in a very small
package.
e.g. Palmtops , Electronic Organizers
TYPES OF COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Microcomputers and Networks
PCs are now found in most businessesUseeither 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 COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Microcomputers and Networks
ServerIn most LANs, one PC is assigned the
role of servermeaning that it stores data and
software for use by the other PCs and/or performs services for them , such as printing
TYPES OF COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Microcontrollers
also called embedded dedicated hidden computers
they are tiny computers installed in ‘smart’ or ‘intelligent’
appliances
TYPES OF COMPUTERSMICROCOMPUTERS
Kinds of Personal Computers ( PCs)Microcontrollers
like pocket calculatorsmicrowave oventraffic lightradiosmobile phones
they are dedicated performing a restricted number of tasks
TYPES OF COMPUTERSSUPERCOMPUTERS
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 COMPUTERSSUPERCOMPUTERS
AspectsFirst developed in the 1970sThe fastest and highest-capacity computersUsed for researchHave hundreds to thousands of processors
TYPES OF COMPUTERSSUPERCOMPUTERS
ExamplesCRAYOPTION 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
Speedbasically 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
Accuracyprovide the microprocessor with the correct instructions
then planned operations can be repeated millions of times without a single errorGarbage In Garbage Out ( GIGO)
concept applieserrors can occurmake errors only when there is a
breakdown in the computing system
CAPABILITIES OF COMPUTERS
Storage capabilitycan 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 capabilitiesthe above three
speedaccuracystorage capability
are fundamental capabilities of computers
by-products of computers
CAPABILITIES OF COMPUTERS
Productivitycan increase productivity
CAPABILITIES OF COMPUTERS
Decision-making Complex situations Using problem-solving techniques Sort things out Do analyses Make choices
CAPABILITIES OF COMPUTERS
Cost Reductionbecause it improves productivity and
aids decision-making ,the computer helps to
eliminate wasteful practiceshold down the cost of labour,
energy and paper work