mode bit

2 definitions found

mode bit - Free On-line Dictionary of Computing (26 May 2007) :

  mode bit
  
     A flag, usually in hardware, that selects between two
     (usually quite different) modes of operation.  The
     connotations are different from flag bit in that mode bits
     are mainly written during a boot or set-up phase, are seldom
     explicitly read, and seldom change over the lifetime of an
     ordinary program.  The classic example was the
     EBCDIC-vs.-ASCII bit (#12) of the Program Status Word of the
     IBM 360.  Another was the bit on a PDP-12 that controlled
     whether it ran the PDP-8 or the LINC instruction set.
  
     [Jargon File]
  

mode bit - Jargon File (4.4.4, 14 Aug 2003) :

  mode bit
   n.
  
     [common] A flag, usually in hardware, that selects between two
     (usually quite different) modes of operation. The connotations are
     different from flag bit in that mode bits are mainly written during
     a boot or set-up phase, are seldom explicitly read, and seldom change
     over the lifetime of an ordinary program. The classic example was the
     EBCDIC-vs.-ASCII bit (#12) of the Program Status Word of the IBM 360.