NEC PD754244 Manuel D’Utilisation

User’s Manual  U10676EJ3V0UM

This is a binary counter that holds an address of the program memory.

PC11

PC10

PC9

PC8

PC7

PC6

PC5

PC4

PC3

PC2

PC1

PC0

The value of the program counter (PC) is usually automatically incremented by the number of bytes of an instruction

each time that instruction has been executed.

When a branch instruction (BR, BRA, or BRCB) is executed, immediate data indicating the branch destination

address or the contents of a register pair are loaded to all or some bits of the PC.

When a subroutine call instruction (CALL, CALLA, or CALLF) is executed or when a vector interrupt occurs, the

contents of the PC (a return address already incremented to fetch the next instruction) are saved to the stack memory

(data memory specified by the stack pointer).  Then, the jump destination address is loaded to the PC.

When the return instruction (RET, RETS, or RETI) instruction is executed, the contents of the stack memory are

set to the PC.

 When the RESET signal is asserted, the contents of the program counter (PC) are initialized to the contents of

address 0000H and 0001H of the program memory, and the program can be started from any address according to

the contents.

PC

11-8

 

← (0000H)

3-0

, PC

7-0

 

← (0001H)

7-0