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4.1
PROGRAM COUNTER (PC) ..... 11 BITS
An 11-bit binary counter to hold the program memory address information.
PC10
The program counter operates as follows.
• Normal operation
The content is incremented automatically according to the number of bytes of the instruction every time one is
executed.
• Branch instruction (BR, BRCB) execution
The immediate data indicating the address of the destination of branching is set in the PC.
• Subroutine call instruction (CALLF) execution and vector interrupt
The content of the PC at that time is saved in the stack memory and then the address of each destination of
branching is set in the PC.
• Return instruction (RET, RETS, RETI) execution
The content of the stack memory is set in the PC.
• RESET input
The low-order 3 bits of the program memory's address 000H is set in PC10 to PC8 and the content of address
001H is set in PC7 to PC0 and then initialized. It is possible to start the program from any address.
CHAPTER 4. INTERNAL CPU FUNCTIONS
CHAPTER 4. INTERNAL CPU FUNCTIONS
Fig. 4-1 Program Counter Configuration
PC9
PC8
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
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