Unformatted text preview: easily move up to the next model without worrying about converting all its existing
The development and introduction of minicomputers also took place during the thirdgeneration period. The computers built till the early 1960s were mainframe systems,
which only very large companies could afford to purchase and use. Clearly, a need
existed for low-cost smaller computers to fill the gaps left by the bigger, faster, and
costlier mainframe systems. Several innovators recognized this need and formed new
firms in the 1960s to produce smaller computers. The first commercially available
minicomputer, the PDP-8 (Programmed Data Processor), was introduced in 1965 by
Digital Equipment Corporation (DEC). It could easily fit in the corner of a room and did
not require the attention of a full-time computer operator. It was based on timesharing
operating system and could be accessed simultaneously by a number of users from
different locations in the same building. Its cost was about one-fourth of the cost of a
traditional mainframe system, making it possible for smaller companies to afford
computers. It confirmed the tremendous demand for small computers for business and
scientific applications, and by 1971 there were more than 25 computer manufacturers
who had entered the minicomputer market.
The characteristic features of third-generation computers are as follows:
1. They were much more powerful than the second-generation computers. They were
capable of performing about l million instructions per second.
2. They were much smaller in size than second-generation computers, requiring smaller
space for installation. 3. Although the heat dissipation was much less than second-generation computers, still
the rooms/areas in which the third-generation computers were located had to be properly
4. They consumed much less power than the second-generation computers.
5. They were much more reliable and less prone to hardware failures than the secondgeneration computers. Hence the maintenance cost was much lower.
They had faster and lar...
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This document was uploaded on 04/07/2014.
- Spring '14