10.1 Roles of an Operating System 323 Keep in mind that the operating system is itself just a program that must be executed. OS processes must be managed and maintained in main memory along with other system software and application programs. The OS executes on the same CPU as the other programs, and must take its turn among them. Before we delve into the details of managing resources such as main memory and the CPU, we need to explore a few more general concepts. Batch Processing A typical computer in the 1960s and ‘70s was a large machine stored in its own heavily air-conditioned room. Its processing was managed by a human operator . A user would deliver his or her program, usually stored as a deck of punched cards, to the operator to be executed. The user would come back later, perhaps the next day, to retrieve the printed results. When delivering the program, the user would also provide a set of sepa-rate instructions regarding the system software and other resources that would be needed to execute the program. Together the program and the
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Computer program, batch processing, modern operating systems