Computer Assisted Instruction (CAI)
History, Evolution, & Future Promise
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Evolution of Computers

ENIAC Limitations

ENIAC computerThe limitations of the ENIAC became obvious very quickly, particularly the fact that to change its function required rewiring a substantial part of the machine, which was a slow process. The solution to this problem is usually attributed to John von Neumann who came up with the "stored-program" concept, in which the sequence of instructions to be performed (called a program) could be entered in much the same way as data stored in the computer to be stored when needed. Being able to do this made rewiring the computer each time unnecessary.

EDSAC, EDVAC & UNIVAC

EDSAC computerThe first machine using this concept was the EDSAC (Electronic Delayed Storage Automatic Computer), which was built at Cambridge University in England in 1949. At the same time, Mauchly and Eckert, the original builders of the ENIAC, contiuned their pioneering efforts and produced their own stored-program computer, the EDVAC, in 1952. Shortly thereafter, they formed a company and sold their first computer, UNIVAC 1, to the Census Bureau.

First-generation computers (1951-1959)

UNIVAC 1 computerThe UNIVAC 1 was the first of what have come to be called first-generation machines. These are typified by using vacuum tubes, by performing slowly (about 1,000 instruction per second),and having a memory capacity of about 16,000 characters of data (the equivalent of about four single-spaced typed pages). It was during this period that the precedent was set for computers to be developed only by large corporations because of the enormous costs involved.

Second-generation computers (1959-1964)

Bell Lab's First TransistorThe era of the first-generation computers ended in 1959 with the replacement of vacuum tubes by transistors. Development of the transistor by three Bell Laboratories scientists, John Bardeen, Houser Brattan, and William Shickley, revolutioned the world. The transistor accomplishes everything a vacuum tube does, uses far less power, and occupies approximately 1/100th of the space. It is also far more reliable and requires no warm-up time. Second-generation computers used transistors rather than tubes, thus increasing their reliability and computational speed, and reducing their volume, cost, and power consumption.

Third-generation computers (1964-1971)

Integrated CircuitThird-generation computers are attributted to the invention of the integrated circuit, or IC. Integrated circuits allow many components to exist on a single small chip. Thus, what had previously been a box full of transistiors and other electronic parts making up the "brain" of the computer could now be packed into an area about 1/4-inch square, known as a chip. IC's are even more reliable than transistors, are cheap to produce, are compact, and use virtually no power at all compared to previous technologies. One of the most important products developed from the integrated technology was the microprocessor. This was a comoputer's "brain" or central processor, completley contained on a single chip the size of a matchbox. With so much power residing on such a small chip, it became possible to build entire computers around it. Thus, microcomputers and minicomputers were born.

Fourth-generation computers (1971 - present)

Large Scale IntegrationOnce the integrated circuit became a reality, the story of further developments centers around how many circuits could be packed on a single silicon chip. Large-scale integration (LSI), for example, made possible the pocket calculator and the digital watch. Advances in microprocessor technology were paralleled by the development of memory chips, that is, chips designed to hold all the zeros and ones needed to express commands in programs. The microprocessor would direct information to be stored in these chips, as well as to be drawn from the chips in the course of executing the programs.

Fifth-generation computers (Present and Beyond)

Artificial Intelligence LogoFifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

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© Created by: Walter Valero, GSLIS 747 - Queens College
Contact: wvalero@york.cuny.edu
Last updated: 15 December 2004
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