simultaneous peripheral operation on-line

1 definition found

simultaneous peripheral operation on-line - Free On-line Dictionary of Computing (26 May 2007) :

  Simultaneous Peripheral Operation On-Line
  
     <operating system, history> (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)