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The 1940's - First Generations
The earliest computers had no operating systems. Machines of the time were so primitive that programs were often entered one bit at time on rows of mechanical switches -
The 1950's - Second Generation
the routine had improved somewhat with the introduction of punch cards. The General Motors Research Laboratories implemented the first operating systems in early 1950's for their IBM 701. The system of the 50's generally ran one job at a time. These were called single-stream batch processing systems because programs and data were submitted in groups or batches.