By now, pretty much everyone has heard the stories about the first computers. They were huge, cost a fortune, required incredible amounts of air conditioning, and perhaps more importantly, ran batch jobs submitted on punched cards and magnetic tape. But even before we had these dinosaurs, there were E.A.M (electric accounting machine) units. They could run one and only one job at a time and you could not share data. One of the major steps in the evolution of computing was sharing data among applications at the same time. Random-access processing wasn’t possible until we got disk-based storage systems.
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