SN8P2711A
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 29
Version 0.1
2.1.4.6 PROGRAM
COUNTER
The program counter (PC) is a 10-bit binary counter separated into the high-byte 2 and the low-byte 8 bits. This
counter is responsible for pointing a location in order to fetch an instruction for kernel circuit. Normally, the program
counter is automatically incremented with each instruction during program execution.
Besides, it can be replaced with specific address by executing CALL or JMP instruction. When JMP or CALL instruction
is executed, the destination address will be inserted to bit 0 ~ bit 9.
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
Bit 1 Bit 0
PC
- - - - - -
PC9
PC8
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
After
reset
- - - - - - 0 0 0 0 0 0 0 0 0 0
PCH
PCL
)
ONE ADDRESS SKIPPING
There are nine instructions (CMPRS, INCS, INCMS, DECS, DECMS, BTS0, BTS1, B0BTS0, B0BTS1) with one
address skipping function. If the result of these instructions is true, the PC will add 2 steps to skip next instruction.
If the condition of bit test instruction is true, the PC will add 2 steps to skip next instruction.
B0BTS1
FC
; To skip, if Carry_flag = 1
JMP
C0STEP
; Else jump to C0STEP.
…
…
C0STEP: NOP
B0MOV
A, BUF0
; Move BUF0 value to ACC.
B0BTS0
FZ
; To skip, if Zero flag = 0.
JMP
C1STEP
; Else jump to C1STEP.
…
…
C1STEP: NOP
If the ACC is equal to the immediate data or memory, the PC will add 2 steps to skip next instruction.
CMPRS
A, #12H
; To skip, if ACC = 12H.
JMP
C0STEP
; Else jump to C0STEP.
…
…
C0STEP: NOP
