Before the introduction of the personal computer or microcomputer to the general market in the 1970s, computers were physically large, complex, often unreliable, and expensive pieces of machinery. However, they operated in much the same way as they do now, loading programs from secondary storage into memory, accepting input, and executing instructions and generating output. Similarities between those early machines and the types that were to follow ended there however—the early machines were manufactured and sold into a small market, as computers were not yet consumer items. The hardware was expensive as semiconductor devices were only just becoming mainstream, and computers of the time were often accommodated in large purpose-built installations that catered to their temperamental operating requirements. The machinery needed air conditioned rooms and was maintained by squads of specialized professionals behind closed doors. As such, computers were out of the realm...