Batch processing
In the early decades of the use of computers, instead of the interactive use of today's computer, users used computers in a Batch processing mode. The operating systems of the time managed just a single process. The most common input devices, at that time, were punch cards, or punch tape. Output was often printed using massive high-speed printers.
Students, or data processing professionals, would sit in a room full of keypunch machines, typing their programs, and possibly their data, on 80 column punch cards. When their card deck was complete they would walk over and stand in a queue, waiting for their turn to the card reader. Each user's card deck would be bracketed by control cards, that marked the end of their "job". Intermittently, the card reader would read a bunch of cards.
Once read in, jobs would held in an electronic queue.
Once a job got the head of the queue it would get loaded into memory, and get exclusive use of the CPU, either until the program(s) in the job finished, or the job's time was up. The time limit would have been determined when the operating system processed the job control cards.
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Keypunch, note the hopper of blank cards, on the right. -
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IBM 3505 Punched Card Reader -
Line printers, like this one, were 132 characters wide. Inside this line printer you see 132 disks, with all the printable characters on the outside of the disk. Paper would flow over the paper. Not shown here there were 132 hammers, one for each disk. The disks would spin very rapidly, and the hammers whip out and strike an ink ribbon, at the precise time to imprint the characters needed for that line. When the line was complete the paper would advance one line. Printers like this could print pages in mere seconds.
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