interrupt
interrupts

    1. An asynchronous event that suspends normal
   processing and temporarily diverts the flow of control
   through an "interrupt handler" routine.

   Interrupts may be caused by both hardware (I/O, timer,
   machine check) and software (supervisor, system call or
   trap instruction).

   In general the computer responds to an interrupt by storing
   the information about the current state of the running
   program; storing information to identify the source of the
   interrupt; and invoking a first-level interrupt handler.
   This is usually a kernel level privileged process that can
   discover the precise cause of the interrupt (e.g. if several
   devices share one interrupt) and what must be done to keep
   operating system tables (such as the process table) updated.
   This first-level handler may then call another handler,
   e.g. one associated with the particular device which generated
   the interrupt.

   2. Under MS-DOS, nearly synonymous with "system call"
   because the OS and BIOS routines are both called using the
   INT instruction (see interrupt list) and because programmers
   so often have to bypass the operating system (going directly
   to a BIOS interrupt) to get reasonable performance.

   [Jargon File]

   (1995-02-07)