Introduction

Abstract

In the past thirty years the influence of computers on our lives has grown dramatically so that there now seems to be no area of man’s activity which is not affected by their use. This rapid infiltration into everyday life has been accompanied by a fall in the price of computer systems, so that now the ‘home-computer’ market seems to be rivalling the hi-fi market. Not many years ago a computer needed to be physically very large and required a special environment to sustain it. Not only that, but computing remained a mystery to the general public and highly-trained, specialised personnel were required to oversee the working of the machines. Due to the rapid advance of technology over the past ten years computers now fall into three main groups. The very large computers are still with us and are referred to as mainframe machines. Such computer installations, an example of which is shown in figure 1, still require special operating environments and large numbers of people to operate them. They are used mainly by the banks, large industrial concerns and the universities. The late 1960s saw the advent of the minicomputer, and because these machines were exceptionally rugged and capable of working in quite primitive conditions, they soon found their way into aircraft, oilrigs, schools, small businesses, and even on to the backs of trucks and tractors. A typical minicomputer installation is shown in figure 2.