06-02-2013, 09:30 AM
Earlier Computers
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INTRODUCTION
The first generation of computers is said by some to have started in 1946 with ENIAC, the first 'computer' to use electronic valves (ie. vacuum tubes). Others would say it started in May 1949 with the introduction of EDSAC, the first stored program computer. Whichever, the distinguishing feature of the first generation computers was the use of electronic valves.
My personal take on this is that ENIAC was the World's first electronic calculator and that the era of the first generation computers began in 1946 because that was the year when people consciously set out to build stored program computers (many won't agree, and I don't intend to debate it). The first past the post, as it were, was the EDSAC in 1949. The period closed about 1958 with the introduction of transistors and the general adoption of ferrite core memories.
OECD figures indicate that by the end of 1958 about 2,500 first generation computers were installed world-wide. (Compare this with the number of PCs shipped world-wide in just the third quarter of 2006, quoted as 59.1 million units by research company Gartner).
Present Computers
In this period, computer technology achieved more superiority and parallel processing, which was until limited to vector processing and pipelining, where hundreds of processors could all work on various parts of a single program. There were introduction of systems like the Sequent Balance 8000, which connected up to twenty processors to one shared memory module.
This machine was as competent as the DEC VAX-780 in the context that it had a general purpose UNIX system and each processor worked on a different user's job. On the other hand, INTEL IPSC-I or Hypercube, as it was called, connected each processor to its own memory and used a network interface to connect the processors. With the concept of distributed network coming in, memory posed no further problem and the largest IPSC-I was built with 128 processors. Towards the end of the fifth generation, another parallel processing was introduced in the devices, which were called Data parallel or SIMD. In this system, all the processors operate under the instruction of a single control unit.