26/07/2003 - AllanaPrepared by Prakash M. Vaidya1 History of Computers Early Developments In Data...

26/07/2003 - Allana Prepared by Prakash M. Vaidya 1

History of Computers

• Early Developments In Data Processing• Punched Card Equipments• Digital Computers• Computer Generations• Types Of Computers• Types of Input Devices• Types of Output Devices• Storage Devices


Early Developments in Data Processing

• The Abacus– Developed by Greeks and Romans with

significant contribution from Chinese.– Additions and subtractions are done by

changing the position of beads.– Significant conceptual contribution of the

Abacus is the use of position to represent value.


• Pascal’s Machine– Blaise Pascal, a French Mathematician and

Philosopher, invented in 1642 a Mechanical Calculator.

– It was a gear driven machine capable of addition, subtraction and multiplication.

– Manipulations were performed by rotating wheels.

– Automatic carry was the significant contribution from Pascal’s machine.


• Modifications to Pascal’s Machine– In 1671 German Mathematician and

Philosopher Gottfried von Leibnitz improved Pascal’s design.

– This machine was capable of addition, subtraction, multiplication and division. It was also able to calculate square roots.

– It consisted of cylindrical drum with nine teeth along its surface. The teeth varied in length, and when the drum rotated, some of them engaged a sliding gear on the axle.

– This gear principle was employed in many mechanical calculators till 1960’s.


• Jacquard’s Loom– In 1801 a Frenchman named Joseph Jacquard

prepared a loom that was controlled by holes in cardboard punched cards.

– The design for woven fabrics was represented by a series of holes punched in the card.

– By sequencing the cards, the loom could produce a large number of patterns and designs.

– Jacquard’s punched cards were a ‘Program’ for the loom. They stored various fabric designs.


• Babbage’s Engines– In 1812 Charles Babbage, an English mathematician

found that certain principals from Jacquard’s loom could be used in numerical computation.

– Babbage devised computing steps that could be stored in advance of computation. He thus developed the concept of the stored program for data processing. He is generally recognized as the first person to propose the concept of computer.

– Babbage designed an analytical engine with four major components viz. input and output devices, an arithmetic unit to perform the calculations and a memory to store intermediate calculations.

– Unfortunately he didn’t succeed in building this machine.


Punched Card Equipments• Metcalfe’s Cards

– In 1870’s Lt Henry Metcalf, at the Frankfor Arsenal in Philadelphia, transferred some of the accounting records from ledgers to cards.

– These cards were similar to index cards normally used by librarians.

– The decks of cards could be manually sorted, summarized and manipulated to meet the information needs of the management.

– This system required a sophisticated coding scheme, a well-defined unit record and a system design that specified the flow of data.


• Hollerith’s Punched Cards– In late 19th century US govt beganto encounter

problems in data processing. It took 7 years to compile the statistics from the 1880 census.

– Hollerith designed a device called tabulating machine. It used machine readable punched cards. His machine reduced tabulating time on 1890 census one-eighth the time required by the old methods.

– In 1911, Hollerith’s Tabulating Machine Company merged with the International Time Recording Company, the Dayton Seale Company, and the Bundy Manufacturing Corp to form Computing-Tabulating-Recording Company (CTR). In 1924, CTR was renamed as International Business Machine Corp. (IBM).


• Powers’s Punched Cards– James Powers, an engineer who worked for the

US Census Bureau, produced several refinements of Hollerith’s machine and patented a punched-card machine in 1908.

– Powers also developed a sorting machine and tabulators that were employed in 1910 US census.

– He later formed Sperry Rand Corporation, which produced UNIVAC computers.


• General Scenario in 1940s– Until the beginning of World War II, only two

companies in US were involved in the Punched Card data processing business viz. IBM that used 80 column Holerith card and Sperry Rand Corporation that used 90 column Powers card.

– The war created great demands for high speed calculating equipment.

– Developments in long-range artillery, aircraft and eventually the atomic bomb required machines that could calculate at very high speed.


Digital Computers

• Harvard Mark I– In 1937, Howard Aiken of Harvard University, began

work on the design of a fully automatic calculating machine in collaboration with the IBM Corporation. Howard’s aim was to develop a machine to help him in the solution of complex differential equations.

– In May 1944, the design became a reality. In August 1944, ‘Harvard Mark I’ was donated to Harvard University. It was initially used for classified work for the US Navy.


– It had taken technology over a century to catch up with the ideas first mooted by Charles Babbage. But once having achieved this a phenomenal rate of development followed.

– The Mark I or Automatic Sequence Controlled Calculator, was complex in design and huge in size.

– Physically the machine measured 51 feet in length and 8 feet in height. It is said to have contained three-quarters of a million parts. It used more than five hundred miles of wire.

– It was extremely slow by present day standards.


• ENIAC– The innovation of very high speed vacuum tube

switching devices led to the first-all electronic computer, the Electronic Numerical Integrator and Calculator (ENIAC). It was dedicated on 15th February 1946, only two years after the Mark I.

– ENIAC was constructed at the Moore School of Engineering of the University of Pennsylvania.

– In a single hour ENIAC could accomplish calculations which would have taken Mark I one week to perform.


• EDVAC– The Electronic Discrete Variable Automatic

Computer – EDVAC – made use of acoustic delay lines consisting of tanks of mercury.

– Both the instructions and the numbers to be used for calculation were stored in the memory unit.

– Prior to EDVAC, EDSAC (Electronic Delay Storage Automatic Calculator) which was developed by British was the first practical computer to operate with an internally stored program.


• Manchester Mark I– It was a small experiment machine built at

Manchester University. It executed its first program in June 1948.

– Its storage capacity was only 32 words, each of 31 binary digits.

– It was too limited to be of any practical use.– This project was set up by Professor Newman,

aided by I.J. Good, F.C. Williams and T. Kilburn.


Computer Generations• No clear cut pattern of development after EDSAC &

EDVAC has emerged.• In order to simplify the matters and provide a

framework for the growth of the computer industry the term of Computer generation was used.

• Originally, the term ‘generation’ was used to distinguish between varying hardware technologies.

• Since 1968, it has been extended to include both the hardware and the software.


• Size & weight of the earlier computers prompted magazine Popular Mechanics to say:

• Computers in the future may weigh no more than 1.5 tons

• In the early years the people who were at the helm of computer industry were also not aware of the potential of the computer industry. "I think there is a world market for maybe

five computers." -- Thomas Watson, chairman of IBM, 1943


• First Generation of Computers (1951-1958)– The first generation of computers was marked by the

use of vacuum tubes for the electronic components and by the use of either electrostatic tubes (cathode ray tubes) or mercury delay lines for storage.

– These computers were very expensive. They were quite large and required special housing.

– The medium of internal storage was magnetic drum.

– Examples of First Generation computers are EDSAC, EDVAC etc.


• Second Generation Computers (1959-1964)– The second generation saw the introduction of printed

circuits and the replacement of valves by transistors.

– In comparison with the previous generation they were smaller in size and generated less heat.

– Internal storage capacity was increased and processor speeds started to be measured in microseconds (millionths) rather than milliseconds (thousandths)

– Magnetic core storage was used rather than magnetic drum.

– Machines started to evolve as series rather than stand-alone processors.


• Second Generation Computers (Contd.)– During this period many punch card machines

became popular. The hardware consisted of• Key punch

• Verifier

• Calculator punch

• Tabulator (it was essentially processor and printer)

• Sorter

• Collator (to merge two batches of cards or to match two batches of cards)

• Reproducer


• Second Generation Computers (Contd.)– In both these generations thousands of separate

components had to be assembled by hand into functioning circuits. It was cost of labour at this assembly stage which became increasingly expensive.

– Introduction of new technology called Integrated Circuits (IC) made it possible to reduce the size and to eliminate the labour costs.

– In 1964 IC s began to be used in computers, thereby ushering in the the third generation.


• Third Generation Computers (1965-1971)– The advances over the previous generation were very

significant. It used small-scale integration (SSI) technique or medium-scale integration (MSI) technique.

– Further reduction in size.

– The cost performance factor has improved significantly.

– Increased internal core memory capacity.

– Increased emphasis on the use of disk as a backing store medium and substantially reduced cost per megabyte.


• Third Generation Computers (Contd.)– Processor speeds are rated in nanoseconds –

1/1000th of a microsecond.– Ranges of computers came into being e.g. IBM-

360, ICL-1900. Models within these ranges were designed to be upward compatible’ thereby enabling systems developed for the lower models in the range to move up the line with limited modification.

– The use of high level languages became common viz. COBOL, FORTRAN and PL/1.


• Fourth Generation Computers (1971-Present)

– Despite of the continued development in the field of computers, people from computer industry were still not able to foresee the future.

– Following are some of the now infamous quotes:• “But what is it good for?“

Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.

• “There is no reason anyone would want a computer in their home”

Ken Olson, president, chairman and founder of Digital Equipment Corp., 1977


• Fourth Generation Computers (Contd.)– It used large-scale integration (LSI) technique.– The distinguishing marks were the introduction

of standard architecture which provided for greater mobility of systems, the introduction of micro-technology and significant software developments.

– This generation gave rise to the availability of microcomputers, word processors and intelligent terminals.


• Fourth Generation Computers (Contd.)– Further reductions in the size of the hardware.

– Better price/performance.

– Hardware which in many cases will operate in a normal office or residential environment.

– Semiconductor memory based on the silicon chip used as core storage. This has led to great expansion in the amount of memory available typically few megabytes as against few kilobytes in the previous generation.

– Cheaper and bigger backing storage devices. Typically single disk drives with capacity of few gigabytes.


• Future Computers– Organic chips

– Decreasing cost of software

– Decreasing cost of hardware

– Super and ultra personal computers

– Increased miniaturization

– Vast performance in the price-performance ratio.

– Applications- artificial intelligence, personal robots, large scale corporate modeling.

– Large storage facility

– High speed


Types of Computers

• Supercomputers• Mainframes• Midrange Machines/Minicomputers• Workstations• Microcomputers• Laptops• Hand Held Computers• Pen Based Computers


• Supercomputers– Supercomputers are fastest and largest

computers available today.– They have large memories and high processing

speeds. They can process up to a billion instructions per second.

– Supercomputers are used for processing very large files and performing large-scale mathematical calculations.

– Supercomputers have multiple processors to do parallel processing.


• Supercomputers (Contd)– Primary disadvantage of supercomputers is

their high cost. The software that runs on them is also very expensive.

– Main applications that use Supercomputers are• Scientific research and R & D• Defense• Geo-science and weather forecasting• Economic and financial modelling• Imaging• Simulatoin• Biological and chemical engineering


• Mainframes– Mainframe is a large, general purpose computer with a

large memory and excellent processing capabilities.

– Mainframes, which are frequently organization wide systems, take their name from ‘main frame’ which once housed the CPU.

– Mainframes serve many users at the same time.

– One of the main disadvantages of the mainframe is that it is expensive to purchase, operate and maintain. Mainframes often require customized software and highly trained computer personnel to run and operate them.


• Mainframes (Contd.)– They are ideal for applications that require

massive computations and large-scale processing.

– The main applications that use mainframes are• Financial applications

• Payroll

• Investment analysis

• Weather forecasting

• Airline & railway reservations


• Midrange Machines/Minicomputers– In the 1970s, Digital Equipment Corporation (DEC)

introduced the concept of a midrange computer, or minicomputer, called the VAX.

– Microcomputers, which are typical work-group systems, are small yet powerful multi-user systems with excellent memory capabilities and processing speeds.

– They are slower than mainframes and often have less memory.

– The introduction of Minicomputers allowed many companies that were unable to afford mainframes to enter the age of computing.


• Workstations– Workstations lie somewhere between minicomputers

and PCs. – They can be used by individuals or by groups.– They are faster and more sophisticated than PCs and

are equipped with a number of productivity tools that increase their efficiency.

– Advances in microprocessors and sophisticated software have significantly increased the capabilities of these machines.

– Some of the popular workstations are• SPARC stations form Sun Microsystems• IBM RS/6000• Hewlett-Packard’s Series 700


• Microcomputers (PCs)– PCs are regarded by many as one of the greatest

invention in history.

– Although the memory size and processing capabilities of microcomputers are less than those of mainframes and minicomputers, advances in hardware technology have made the PC a compact, powerful and versatile machine.

– PCs have given the ability to users to plug in different hardware and software components and customize their PCs to meet their own personal requirements.


• Laptops and Notebooks– Laptops and notebooks provide mobile

computing technology.– Primary differences between a laptop and a

notebook are size and weight. Notebooks are smaller than laptops. However,both are are equipped with powerful microprocessors, graphics capabilities and adequate memory size.


• Hand-Held Computers– Hand-held computers are even smaller than

notebooks.– They are primarily used to collect field data. – Common applications where Hand-held

computers are used are:• Sales Representatives.

• Archaeologists at a dig site.

• Mobile police force in US.


• Pen Based Computing– Pen base computing refers to portable

computers that use an electronic writing pad and a light sensitive electronic pen, thus freeing users from the constraints of a keyboard.

– Pen-based computing is becoming increasingly popular because many people are comfortable using a pen.

– It is particularly popular in sales and service representatives and other people who are often on the move.


Types of Input Devices

• Keyboard

• Scanning Devices

• Voice Input Devices

• Pointing Devices

• Touch-Tone Devices


• Scanning Devices– Bar Code Readers

• They have proved to be very valuable as data entry devices for two reasons viz. The price and product inventory numbers do not need to be keyed in and the online real-time sales data and inventory status is always available.

– Optical Mark Readers (OMR)• It is the simplest form of optical data recording. OMR device

has a high-intensity light inside that is directed in the form of a beam at the sheets of paper being fed through.

• They come in a variety of sizes and shapes.

• Popular application that uses these devices are different competitive examinations.


• Scanning Devices (Contd.)– Typewritten and Typeset-character scanners

• These devices were introduced to help speed up and reduce the cost of converting typewritten data to computer usable form.

– Handwritten-Character Readers• Although the percentage of data recorded by hand

has dropped substantially over the last 50 years, quite a bit of data is still recorded this way. As OCR technology advanced, it also became possible to convert handwritten data into computer usable forms.


• Scanning Devices (Contd.)– Magnetic Ink Character Recognition (MICR)

• This technology is mainly used in banking industry. Advantages of MICR system are human involvement is minimal and it is fast, automatic and reliable.

– Smart Cards• Smart cards were pioneered in the mid 1970s in

France.Smart cards have microchips that can keep permanent records, which are updated each time the card is used. They are used in Europe and US to pay bills, buy merchandise, make phone calls, store emergency medical information etc.


• Voice Input Devices– In an effort to increase worker productivity, a

substantial amount of research is being done in voice recognition.

– These devices convert spoken words into computer usable form.

– This technology is also used by people who are not able to use traditional input devices.

– Several voice input units are currently available for use with PCs.


• Pointing Devices– Light Pen

• It uses a light-sensitive photoelectric cell to signal screen position to the computer. Light pens are frequently used by graphical designers, illustrators and drafting engineers.

– Mouse• The mouse can be use like a pen or a paintbrush to create

figures and patterns .

– Touch Screen• Limited amounts of data can be entered via terminal or a PC

that has a touch screen.

– Digitizer• The digitizing tablets are the working surface. Each is covered

by a grid of many tiny wires that is connected to computer. Drawings placed over this grid can be traced and entered into the computers.


Types of Output Devices

• Hard Copy Output Devices• Softcopy Output Devices• Voice Output Systems


• Hard Copy Output Devices• Letter Quality Printers

– Letter quality printers, also called character printers or serial because they print one character at a time. It is normally used for important business letters, memos and reports.

• Dot-Matrix Printers– These are also called as serial printers. They have

greater speed and more flexibility.

– The print head of a dot-matrix printer usually has nine pins. However, high quality dot matrix printers have print heads with 24 pins.


• Dot-Matrix Printers (Contd.)– Speed of dot matrix printers ranges from 50 cps

to 400 cps.

• Line Printers– They are so called because they print a whole

line of characters at one.– Their speed ranges from 200 to 3,000 lines per

minute.– Major disadvantages of line printers are noise

and relatively poor image quality.


• Ink-Jet Printers– Ink-jet printers work in much the same fashion as dot

matrix printers in that they form images or characters with little dots. However, the dots are formed, not by hammer like pins, but by tiny droplets of ink. These printers have speed similar to dot matrix printers.

• Laser Printers– This technology is much less mechanical than impact

printing, resulting in higher speeds and quieter operation. The process resembles the operation of a photocopy machine. The major advantages are high speed, low noise level and very high image quality.


• Plotters– A plotter is a specialized output device

designed to produce high-quality graphics in a variety of colours. Different types of plotters are available viz. drum plotter, flatbed plotter and electrostatic plotters. Drum and flatbed plotters use pens. Electrostatic plotters are faster than pen plotters and can produce images of very high resolution.


• Softcopy Output Devices– Monochrome and Color Monitors– Liquid Crystal Display (LCD)

• The principal advantages of LCD are low power consumption, low cost and small size.

• Main disadvantages of LCD are it does not emit light; as a result the image has very little contrast and screen is very susceptible to glare, so the optimum viewing angle is very narrow.


• Gas Plasma Display– It is the oldest flat screen technology in use.The

main advantages of it are:• The images are much brighter than on a standard

CRT.• The resolution is excellent.• Glare is not a significant problem.• The screen does not flicker like some CRTs.

– Its main disadvantages are:• Only a single color is available (reddish orange)• The technology is expensive.• It uses a lot of power.


• Voice Output Systems– Voice output systems are relatively new and can be

used in some situations where traditional display screen softcopy output is inappropriate.

– Two different approaches to voice output have evolved viz. speech coding and speech synthesis.

– Speech coding relies on human speech as a reservoir of sounds to draw from in building the words and phrases to be output. Speech coding has been used in applications such as automobiles, toys and games.

– Speech synthesis relies on the use of a set of basic speech sounds that are created electronically without the use of a human voice.


Storage Devices

• Magnetic Tapes

• Diskettes


• Magnetic Tapes– Faster, more convenient and more cost-effective means

than punched cards– Magnetic tape is a plastic tape coated with

magnetizable iron oxide.– A modern tape storage unit can store the equivalent of

more than 2.25 million punched cards.– It is widely used in minicomputers and mainframe

computers– Limitations of Magnetic tapes:

• Data recorded on tape can not be practically altered. When records need to be changed, added, deleted or modified a completely new tape must be created.

• The data is recorded on the tape sequentially and can be accessed only sequentially.


• Floppy Disks– Like magnetic tapes, floppies are made of a

special plastic that can be coated and easily magnetized.

– The initial diskette introduced by IBM was 8 inches in diameter.

– IBM introduced 5 ¼ inch diskettes in their PCs in 1981 while Apple introduced 3 ½ inch diskettes in 1984.

– The capacity of diskettes ranges from 360 KB to 1.44 MB


• Hard Disks– The introduction of high-capacity of hard disks

for PCs solved problems related to limited storage capacity.

– Hard disk technology was first introduced by IBM in the early 1970s.

– Hard disks for PCs began to appear in 1980s.– Initial capacity of Hard Disks for PCs was in

the range of 10MBs.


• Disk Cartridges– Removable disk cartridges are an alternative to hard

disk units as a form of secondary storage.

– Their capacity is normally lower than hard disk units but still substantially superior to floppies.

• Cartridge Tape Units– As high-capacity hard disk units increased in

popularity, the problem of making backup copies of disk contents became a significant concern.

– This concern prompted the development and refinement cartridge-tape units.


• CD-ROM / CD-ROM Drive– The user cannot erase it, change it or write on this disk.

– The user can only read the data.

– Typical storage capacity of CD is 700/800 MB.

• WORM CD (Write Once, Read Many)– The user cannot erase it or change it

– The user can write the data once.

• CD R/W– The user can write data many times.

– User can also erase or change the data.

26/07/2003 - AllanaPrepared by Prakash M. Vaidya1 History of Computers Early Developments In Data...

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