system call

from WordNet (r) 3.0 (2006)

system call
    n 1: an instruction that interrupts the program being executed
         and passes control to the supervisor [syn: {system call},
         {supervisor call instruction}]

from The Free On-line Dictionary of Computing (8 July 2008)

system call

   <operating system, programming> The mechanism used by an
   {application program} to request service from the {operating
   system}.  System calls often use a special {machine code}
   instruction which causes the processor to change mode (e.g. to
   "supervisor mode" or "{protected mode}").  This allows the OS
   to perform restricted actions such as accessing hardware
   devices or the {memory management unit}.

   (1995-03-01)