NB: This page is not related to the IB Computer Science Syllabus

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Some Historical Background

On this page:  [ Mechanical | 1st Generation | 2nd Generation | 3rd Generation ]

                        [ 4th Generation | 5th Generation | von Neumann | Alan Turing ]

Mechanical device

Of the forerunners to electronic computers the most notable were those of Charles Babbage (1791-1871) who developed mechanical devices with the key components we see in computers today: input devices (punched cards), processor (including mechanical storage of data) and output devices (printed cards). The first computer programs were developed for Babagge's machines by Ada Byron (Countess of Lovelace, 1815-1852), niece of the famous poet. The US Government's official programming language, Ada is named for the Countess. George Boole (1815-1864) developed the system of logic (Boolean logic) used in electronic computers today, although at the time he worked on it there were no practical applications for it.

First generation electronic - valves

Early experimental electronic computers such as ENIAC and EDVAC in the USA ( John Mauchley and J Presper Eckert ), The Manchester Mark 1 in the UK ( Alan Turing ) and the first commercial computer - UNIVAC operated using thermionic valves ( more simply, just valves). Because the power requirement of valves was high and their size relatively large (about the size of a small light bulb) these machines were monsters. they were horrifically expensive to build and maintain and were serviced and operated by a very few specialists. For example, ENIAC was 30 metres long and 3 metres high. Comparison of ENIAC and modern microprocessor

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Second generation - transistors

In 1948 William Shockley , John Bardeen and Walter Brattain ) invented the transistor which worked in a similar way to a valve but was very much smaller and had much lower power requirements. It was the basis of second generation machines which themselves were smaller and lighter and consumed much less power.

Third generation integrated circuits

This was followed by the wider spread of computers in commerce and the major manufacturers were able to develop and research new devices such as the integrated circuit (invented by Jack Kilby in 1958) which contained the equivalent of many hundreds of transistors, the third generation.

Fourth generation - smaller, transportable devices

Further miniaturisation led to the development of smaller computers (up to now we have used the term to apply only to mainframes) such as the minicomputer and, in the late 70's, the microcomputer. These are fourth generation machines. Decreasing size and complexity coupled with increasing computing power have had a tremendous impact on society (especially western industrial) and the final effects of the information revolution can only be a matter of guesswork.

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Fifth generation -AI

Fifth generation machines under development for a couple of decades now are expected to display considerable artificial intelligence . The problems of introducing intelligence into the computer is a task that was greatly under-estimated and the search for an intelligent machine has led to considerable discussion on what constitutes human intelligence.

Further miniaturization led to the development of smaller computers (up to now we have used the term to apply only to mainframes) such as the minicomputer and, in the late 70's, the microcomputer. These are fourth generation machines. Decreasing size and increasing computing power have had a tremendous impact on society (especially western industrial) and the final effects of the information revolution can only be a matter of guesswork.

There are many interesting sites on the web where you can read about the history of computing in greater detail:

[ This site has excellent links to Computer History on the web ]

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Von Neumann

Something of a character by all accounts, John Von Neumann (1903-1957) collaborated with John Mauchley and J Presper Eckert , Jr at the Moore School in the University of Pennsylvania. They had constructed the ENIAC computer and, later built the EDVAC in which data and instructions were coded in binary and stored together in computer memory. The stored program concept , as it came to be known, is generally ascribed to Von Neumann who wrote the key research paper about it. Historians agree that Eckert and Mauchly first conceived the concept. It was a significant step forward since the ability to store, and therefore change, the program in computer memory allowed the machine to became a general-purpose device. The storing of data and instructions in binary code also enabled the relatively straightforward transfer of data between computers and peripherals. In the Von Neumann machine the processor fetches every instruction from computer memory, decodes and executes it.

[ more info on John von Neumann ]

 Turing

Alan Turing (1912-1954) was an eccentric genius who worked on early computers in the UK. His team built Colossus, the first electronic calculating machine which was used to assist code-breaking during the second world war. Turing was a brilliant theoretician too and gave his name to the Turing test of artificial (machine) intelligence and to the Turing Machine - a theoretical processor capable of modelling any digital computation on any computer. The Turing machine (remember it's an abstract model not a real machine) consists of an endless recording tape running past a read-write head which can write onto the tape only the symbols 1 and 0. Those who are interested can explore the operation of the Turing machine more fruitfully and enjoyably with the demonstration program written by John Kennedy of Santa Monica College Maths Department.

[ more info on Alan Turing ]

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