mainframes

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Learning About MAINFRAMES

MAINFRAMES

Since the fist UNIVAC I was sold in 1951, the mainframe computer has been the cornerstone of the computer industry. IBM, the giant of the computer industry, captured the mainframe market in the late 1950’s and made its name and fortune manufacturing mainframe computer systems. Mainframes are the most widely used type of computer in medium and large-sized businesses. IBM still holds and estimated two-thirds of the mainframe market.

The typical mainframe computer occupies much of a large room. Like supercomputers, mainframes require an environment with closely monitored humidity and temperature. Mainframes cost considerably less than supercomputers; most mainframe computers are priced between $100,000 and $2,000,000.

For input-output intensive-operations, mainframe computers are much more suitable than supercomputers. Many modern mainframes have multiprocessing capabilities; however, they are generally limited to eight or fewer processors. The processors in mainframes are slower than those in supercomputers.

A mainframe computer system is usually composed of several computers in addition to the mainframe, or host processor. The host processor is responsible for controlling the other processors, all the peripheral devices, and the mathematics operations. A front-end processor is responsible for handling communications to and from all the remote terminals connected to the computer systems. Sometimes a back-end processor is used to handle data retrieval operations. Although the host computer could perform all these operations, it can be used more efficiently if relieved of time consuming chore that do not require processing speed.

Mainframe computer systems are powerful enough to support simultaneously several hundred users at remote terminals. Terminals can be located near the computer or miles away. Computers can support hundreds of users by keeping numerous programs in primary memory and rapidly switching back and forth between programs. Because computers are so much faster than people, the users never notice that the computer is handling other tasks. This capability to process concurrently numerous programs for multiple users is known as multiprogramming.

Sales of mainframe computers have been declining since the 1980’s, which brought the introduction of the microcomputer and the increased capabilities of minicomputers. Recently, to bolster sales of mainframes, IBM started producing mainframes based on arrays of microprocessor chips and designed to be servers for giant databases for networks of microcomputers.

Last updated  2008/09/28 02:26:40 CDTHits  3124