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THE MECHANICAL ERA
A machine inspired by Babbage's design was arguably the first to be used in computational science. George Scheutz read of the difference engine in 1833 and along with Edvard Scheutz began work on a smaller version. 1853 they had constructed a machine that could process 15-digit numbers and calculate fourth-order differences.Their machine won a gold medal at the Exhibition of Paris in 1855 and they sold it to the Dudley Observatory in Albany New York which used it to calculate the orbit of Mars -
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FIRST GENERATION ELECTRONIC COMPUTERS
Three machines have been promoted at various times as the first electronic computers. Machines used electronic switches, in the form of vacuum tubes instead of electromechanical relays. Electronic components had one major benefit, however: they could ``open'' and ``close'' about 1,000 times faster than mechanical switches.A second early electronic machine was Colossus, designed by Alan Turing for the British military in 1943 -
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SECONF GENERATION
Electronic switches in this era were based on discrete diode, transistor technology with a switching time of approximately 0.3 microseconds. The first machines to be built with this technology include TRADIC at Bell Lab in 1954 and TX-0 at MIT's Lincoln Lab. Memory technology was based on magnetic cores which could be accessed in random order in which data was stored as an acoustic wave that passed sequentially through the medium and could be accessed only when the data moved by the I/O interf. -
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THIRD GENERATION
The third generation brought huge gains in computational power. Innovations in this era include the use of integrated circuits, or ICs (semiconductor devices with several transistors built into one physical component), semiconductor memories starting to be used instead of magnetic cores, microprogramming as a technique for efficiently designing complex processors, the coming of age of pipelining and other forms of parallel processing , and the introduction of operating systems and time-sharing. -
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FOURTH GENERATION
The next generation of computer systems saw the use of large scale integration (LSI - 1000 devices per chip) and very large scale integration (VLSI - 100,000 devices per chip) in the construction of computing elements. At this scale entire processors will fit onto a single chip, and for simple systems the entire computer (processor, main memory, and I/O controllers) can fit on one chip. Gate delays dropped to about 1ns per gate. -
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FIFTH GENERATION
The development of the next generation of computer systems is characterized mainly by the acceptance of parallel processing. Until this time parallelism was limited to pipelining and vector processing, or at most to a few processors sharing jobs.The scale of integration in semiconductors continued at an incredible pace - by 1990 it was possible to build chips with a million components - and semiconductor memories became standard on all computers. -
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SIXTH GENERATION
This gen is beginning with many gains in parallel computing, both in the hardware area and in improved understanding of how to develop algorithms to exploit diverse, massively parallel architectures. Parallel systems now compete with vector processors in terms of total computing power and most expect parallel systems to dominate the future.Explosive growth of wide area networking. Network bandwidth has expanded tremendously in the last years and will continue to improve for the several years.