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program counter[′prō·grəm ‚kau̇nt·ər]
(PC, or "instruction address register") A register in the central processing unit that contains the addresss of the next instruction to be executed. The PC is automatically incremented after each instruction is fetched 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.