SN8P2501D
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 25 Version 1.5
If the destination decreased by 1, which results underflow of 0x01 to 0x00, the PC will add 2 steps to skip next
instruction.
DECS instruction:
; Jump to C0STEP if ACC is not zero.
DECMS instruction:
; Jump to C0STEP if BUF0 is not zero.
MULTI-ADDRESS JUMPING
Users can jump around the multi-address by either JMP instruction or ADD M, A instruction (M = PCL) to activate
multi-address jumping function. Program Counter supports “ADD M,A”, ”ADC M,A” and “B0ADD M,A” instructions
for carry to PCH when PCL overflow automatically. For jump table or others applications, users can calculate PC value
by the three instructions and don’t care PCL overflow problem.
Note: PCH only support PC up counting result and doesn’t support PC down counting. When PCL is
carry after PCL+ACC, PCH adds one automatically. If PCL borrow after PCL–ACC, PCH keeps value and
not change.
Example: If PC = 0323H (PCH = 03H, PCL = 23H)
Example: If PC = 0323H (PCH = 03H, PCL = 23H)
; PCL = PCL + ACC, the PCH cannot be changed.
; If ACC = 0, jump to A0POINT
; ACC = 1, jump to A1POINT
; ACC = 2, jump to A2POINT
; ACC = 3, jump to A3POINT
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