Maxim Integrated MAXQ Family - Manual (Page 213)

18-36
MAXQ Family User’s Guide
SUB/SUBB src Subtract /Subtract with Borrow
Description: Subtracts the specified src from the active accumulator (Acc) and returns the result back to the active accumula-
tor. The SUBB additionally subtracts the borrow (Carry Flag), which may have resulted from previous subtraction.
For the complete list of src specifiers, reference the MOVE instruction. The MAXQ20 may use the PFX[n] register to
supply the high byte of data for 8-bit sources.
Status Flags: C, S, Z, OV
SUB Operation: Acc ← Acc - src
Encoding: 15 0
MAXQ10
Example(s):
; Acc = 23h to start, A[1]= 12h
SUB A[1] ; Acc = 11h, C=0, S=0, Z=0
SUB A[1] ; Acc = FFh, C=1, S=1, Z=0
MAXQ20
Example(s):
; Acc = 2345h to start, A[1]= 1250h
SUB A[1] ; Acc = 10F5h, C=0, S=0, Z=0, OV=0
SUB A[1] ; Acc = FEA5h, C=1, S=1, Z=0, OV=0
SUB A[2] ; A[2] =7FFFh
; → Acc = 7EA6h; C=0, S=0, Z=0, OV=1
SUBB Operation: Acc ← Acc - (src + C)
Encoding: 15 0
MAXQ10
Example(s):
; Acc = 23h, A[1]= 12h, C=1
SUBB A[1] ; Acc = 10h, C=0, S=0, Z=0
SUBB A[1] ; Acc = FEh, C=1, S=1, Z=0
SUBB #0Dh ; Acc = F0h, C=0, S=1, Z=0
MAXQ20
Example(s):
; Acc = 2345h, A[1]= 1250h, C=1
SUBB A[1] ; Acc = 10F4h, C=0, S=0, Z=0
SUBB A[1] ; Acc = FEA4h, C=1, S=1, Z=0
Special Notes: The active accumulator (Acc) is not allowed as the src for these operations.
f101 1010 ssss ssss
f111 1010 ssss ssss
Maxim Integrated