[W/K] :: Simultaneous Peripheral Operation On-Line

  Simultaneous Peripheral Operation On-Line
       
           (SPOOL) Accessing peripheral
          devices with the help of an off-line tape drive.  The term
          was derived by IBM for use with the IBM 360 operating
          systems.
       
          In the early days of computing (early 1960s), before
          multitasking was invented, computers (e.g. IBM 704) could
          run only one job at a time.  As peripheral devices such as
          printers or card readers were much slower than the CPU,
          devoting the computer (the only computer in many cases) to
          controlling such devices was impractical.
       
          To free the CPU for useful work, the output was sent to a
          magnetic tape drive, which was much faster than a printer
          and much cheaper than a computer.  After the job was finished
          the tape was removed from the tape drive attached to the
          computer and mounted on a tape drive connected to a printer
          (such as the IBM 1403).  The printer could then print the
          data without holding up the computer.  Similarly, instead of
          inputting the program from the card reader it was first copied
          to a tape and the tape was read by the computer.
       
          (1999-01-12)