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The Computer Generations ?


1. THE FIRST GENERATION ( 1951 – 1958 )

              The Vacuum tube was the primary electronic element used in first generation computers. These early computers, while useful, were still quite unreliable. Vacuum tubes generated so much heat that water cooling was necessary. Even with these cooling systems, computers were in constant need of repair.

Remington Rand delivered the first UNIVAC I to the US Bureau of the Census in 1951. This marked the first time an electronic computer had been built for a data processing application rather than a military one. By 1952, the Census Bureau had obtained three UNIVACs, which displaced much of the punched card equipment that IBM had sold the Bureau. IBM was forced to take a hard look at this new data processing technology.

Thomas Watson Jr. IBM’s new president directed IBM toward electronic computers and away from Electro Mechanical Punched Equipment.

First generation computers used Vacuum tubes for data storage in ALU (Arithmetic and Logic Unit) and CU ( Control Unit ) units as well as in Primary Memory. By the end of this era, the faster Magnetic Cores being used for Primary Memory.

Data and programs were entered most often by punched cards; computer output was produced either on cards or on paper. Cards were the primary form of storage, but by the end of this time period, Magnetic Tapes were commonly used for secondary storage.

Work to improve the Transistor continued through out the 1950s. After using the larger Vacuum Tubes working with Transistors was rather like doing surgery on the head of a pin, but by 1958, advances in Transistors were bringing the first computer generation to an end. The leading electronic circuit technology at that time stacked components on top of one another, like dishes, with connecting wires running up through holes cut in the components.


              First generation computers had very skimpy, if any, operating systems. Instead a human operator loaded a stack of cards containing a program and data, which were processed as a batch. Military computers such as SAGE Air Defense System, lead to new system’s software able to handle remote data entry and to link computer systems together in networks.

All computers are directed by machine language instructions. Each instruction takes the form of a series of binary digits. The very first computers such as the ENIAC, were actually directly programmed in machine language, which was very difficult and time consuming.

By the early 1950s, though most programming was being done in assembly languages in which abbreviations replaced the binary digits of machine language. Assembly language programs are often translated to machine language instructions by system’s software known as Assembler. Both machine assembly languages require programmers to work at the level of a computer’s electronic circuitry.

In 1954, a group of IBM scientists lead by John Backus began work on the design of a high level programming language for scientific computing. This language was called as FORTRAN. With high level programming languages, program instructions are directed toward the problem being solved rather than the computer on which the program is run. As a result a single program instruction may represent a series of machine language instructions. The important part in the high level language is that they have to be “translated “in to machine language. This is performed by a system’s software program called Compiler.

FORTRAN was available by 1956 and in general use by 1957. By the end of 1950s, over two hundred other high level programming languages had been developed. IBM’s development of the 705 series of Business Computers in 1955 proved to be an important mile stone in the history of computers.


2. THE SECOND GENERATION ( 1959 – 1963 )

                    The Appearance in 1959 of the first transistorized computer systems launched the second generation of computers. In 1960 Digital Equipment Corporation ( DEC ) introduced the first Minicomputer. This Minicomputer differed from regular computer systems in a number of ways. They are small and also built for special purposes.  They can perform even in harsh environments with fewer climate controls needed. Also they were less expensive. With these improvements, computer systems began to be used in new environments such as Laboratories and Factories. The other notable events in this era were

a.      IBM began work on its System 360 series of Computers.

b.      Launching of the Telstar communications satellite.


Though second generation computers used transistors for most processing circuitry, magnetic cores were still used for primary memory. Most data and programs were entered in to the computer from magnetic tape. Often, however data would first be punched on cards and often copied in to tapes to speed data entry. Similarly, output was often directed to tape to be printed on to paper later. While magnetic tapes were the most common secondary storage devices, magnetic disks did appear toward the end of this era.


The first real operating systems appeared during this period. Besides improving computer system efficiency, these operating systems brought about new forms of data processing such as

        – Interactive Processing

        – Real Time Processing

        – Time Sharing Processing

Example : SABRE Reservation System – Developed by IBM and American Airlines allowed reservation clerks to interactively review or update a flight’s data as reservations were being made. Major Developments in the Programming Language during this period was

     – COBOL ( Common Business Oriented Language )
     -  BASIC    ( Beginners All purpose Symbolic Instruction Code )
     -  PL /1 ( Programming Language One )


3. THE THIRD GENERATION ( 1964 – 1970 )

         In 1964 IBM introduced the six computers that made up the System 360 family of computer systems. With software controlling all aspects of computer’s operation, efficiencies improved and failures were less frequent. As a result firms became more willing to depend on computer systems to handle all their information processing needs.

Major Developments were

- The development of the magnetic tape type writer made it possible for typists to store and retrieve documents.

- DECs success with its PDP-8 Minicomputer spurred other firms to enter the Minicomputer segment of the computer industry.

- Responding to possible US Department of Justice antitrust actions, IBM “unbundled” its software.


By 1964, some of the transistors and magnetic cores had been replaced by Integrated Circuits


          Operating Systems continued to grow in power. More programming languages were also developed. IBM developed RPG (Report Program Generator) to aid small business switching from punched cards to electronic computers. In 1971, Nicholas Wirth developed the PASCAL language. This was the first programming language to use structured programming concepts.


4. THE FOURTH GENERATION ( 1971 – Present )

Instead of having one simple electronic circuit in a silicon chip, large scale integration technology ( LSI ) places many circuits within a single chip. During this fourth generation of computing, LSI technology has improved to where first hundreds, then thousands and now hundreds of thousands of electronic components are manufactured as a single chip. The term Very Large Scale Integration ( VLSI ) is used when referring to these very high chip densities. With LSI and VLSI technologies computers have become even smaller, faster, more reliable and less expensive.

A key development of this fourth generation of computers was the development of Microprocessor in 1971. In the summer of 1969, BUSICOM , a Japanese Calculator Manufacturer, approached INTEL with a contract to design a set of chips for a new family of calculators. At least 12 chips were required in BUSICOMs initial plans. At Intel this 12 chips were whittled to 4, one of which, the Intel 4004 Microprocessor, which contained all the logic and control circuits.

Other Major Developments were:

-Intel’s earliest microprocessors, the 4004 and 8008 were designed for special purposes. In 1974, Intel developed the Intel 8080, a microprocessor suited for general purpose computing.

- MITS (Micro Instrumentation and Telemetry Systems) in 1975 developed the first commercially successful Microcomputer, the Altair which sparked Microcomputer Revolution.

            – Steven Jobs and Steven wozniak formed Apple Corporation in 1977 to build and sell Apple II computers.

- IBM PC 5150 ( 1981 ) met with overwhelming acceptance by business and Microcomputer market exploded.

-Toshiba 3100 Computer ( Laptop ) is the first Microcomputer to have a full – screen plasma display.

-The announcement that, Expansion Boards holding an Intel’s 80286 Microprocessor could be fitted in to Apple Corporations latest computers, the Macintosh SE and Macintosh II suggests that the de facto standard is now official.

- The appearance of Microcomputers using 32 Microprocessors, such as Motorola’s 68020 chip and Intel’s 80386 chip, are finally enabling Microcomputers to operate software in a fashion similar to large computer systems. Among the first Microcomputers notable ones are:

        a. Compaq Desktop Pro 386
        b. Apples Macintosh II
        c. IBM PS/2 Model 80

- Electronic Spreadsheet and Word Processing softwares provided immediate and significant benefits to business users ( Visi Calc of Aplle II, Lotus 1-2-3 and Wordstar of IBM PC )

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