DS80C320-MCG Datasheet, PDF (66/175 Pages) Dallas Semiconductor – High-Speed Microcontroller User Guide

High-Speed Microcontroller User’s Guide
PROGRAM STATUS FLAGS
All Program Status Flags are contained in the Program Status Word at SFR location D0h. It contains
flags that reflect the status of the CPU and the result of selected operations. The flags are summarized
below. The following table shows the instructions that affect each flag.
Bit Description :
PSW.7
Carry
C
Set when the previous operation resulted in a carry (during addition) or a
borrow (during subtraction), otherwise cleared.
PSW.6
Auxiliary Carry
AC
Set when the previous operation resulted in a carry (during addition) or a
borrow (during subtraction) from the high order nibble. Otherwise cleared.
PSW.2
Overflow
OV
Set when a carry was generated into the high order bit but not a carry out of
the high order bit. OV is normally used with 2’s complement arithmetic.
PSW.0
Parity
P
Set to logic 1 to indicate an odd number of ones in the accumulator (odd
parity). Cleared for an even number of ones. This produces even parity.
All of these bits are cleared to a logic 0 for all resets.
INSTRUCTIONS THAT AFFECT FLAG SETTINGS Table 4-4
INSTRUCTION
FLAGS
INSTRUCTION
FLAGS
C
OV AC
C
OV AC
ADD
X
X
X
CLR C
0
ADDC
X
X
X
CPL C
X
SUBB
X
X
X
ANL C, bit
X
MUL
DIV
0
X
ANL C, bit
X
0
X
ORL C, bit
X
DA
X
RRC
X
ORL C, bit
X
MOV C, bit
X
RLC
X
CJNE
X
SETB C
1
X indicates the modification is according to the result of the instruction.
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