Introduction to computers and their development

Abstract

A data processing system can be a calculator, a bookkeeping machine, or a computer. Computers are based upon these five basic elements: a control unit, an arithmetic unit, memory unit, input unit, and output unit. Historically, first generation systems were physically large, able to be programmed only by bit manipulation machine language, very slow, and required extensive air conditioning and atmospheric control. Second generation computers saw the transition from electronic tubes to transistorized circuits speeding up internal processing. High levels compilers and assemblers were introduced, enabling programs to be written on a one-for-one assembly language basis, or on a two-to-one, three-to-one or more basis by using a compiler. Third generation systems saw significant improvements in utilization of microminiaturized circuits and interrupt handling that permitted development of complex operating systems including extensive progress in the area of time sharing and communications uses. Additional computers, first introduced in 1960, are the minicomputers. These minicomputers usually function in a dedicated environment and have many characteristics originally found in the third generation systems as well as many unique qualities of their own. Characteristics that categorize a computer as being a “mini” include purchase price of less than $25,000 at introduction, a memory size of 4000 bytes or more, minimal system configuration, and, usually, outright purchase. Minicomputer manufacturers are finding a large market for their product with dedicated applications and the original equipment manufacturer. The minicomputer may be the basis for still another generation of computers.