program counter

    (PC) A register in the central processing unit
   that contains the addresss of the next instruction to be
   executed.  After each instruction is fetched, the PC is
   automatically incremented to point to the following
   instruction.  It is not normally manipulated like an ordinary
   register but instead, special instructions are provided to
   alter the flow of control by writing a new value to the PC,
   e.g. JUMP, CALL, RTS.

   IBM call it the Instruction Address Register.

   (1995-03-21)