beautypg.com

4 program counter (pc), Program counter (pc) – FUJITSU F2MCTM-16LX User Manual

Page 61

background image

45

CHAPTER 2 CPU

2.7.4

Program Counter (PC)

The PC register is a 16-bit counter that indicates the low-order 16 bits of the memory
address of an instruction code to be executed by the CPU. The high-order eight bits of
the address are indicated by the PCB. The PC register is updated by a conditional
branch instruction, subroutine call instruction, interrupt, or reset.
The PC register can also be used as a base pointer for operand access.

Program Counter (PC)

Figure 2.7-10 shows the program counter.

Figure 2.7-10 Program Counter

PCB

PC

FE

H

ABCD

H

FEABCD

H

Next instruction to be executed