Appendix C Status Flag Summary

Status Flags' Functions

Bit  Name   Function

 0   CF     Carry Flag -- Set on high-order bit carry or borrow; cleared
            otherwise.
 2   PF     Parity Flag -- Set if low-order eight bits of result contain
            an even number of 1 bits; cleared otherwise.
 4   AF     Adjust flag -- Set on carry from or borrow to the low order
            four bits of   AL; cleared otherwise. Used for decimal
            arithmetic.
 6   ZF     Zero Flag -- Set if result is zero; cleared otherwise.
 7   SF     Sign Flag -- Set equal to high-order bit of result (0 is
            positive, 1 if negative).
11   OF     Overflow Flag -- Set if result is too large a positive number
            or too small a negative number (excluding sign-bit) to fit in
            destination operand; cleared otherwise.

Key to Codes

T     = instruction tests flag
M     = instruction modifies flag
        (either sets or resets depending on operands)
0     = instruction resets flag
--    = instruction's effect on flag is undefined
blank = instruction does not affect flag



Instruction            OF   SF   ZF   AF   PF   CF
AAA                    --   --   --   TM   --   M
AAS                    --   --   --   TM   --   M
AAD                    --   M    M    --   M    --
AAM                    --   M    M    --   M    --
DAA                    --   M    M    TM   M    TM
DAS                    --   M    M    TM   M    TM
ADC                    M    M    M    M    M    TM
ADD                    M    M    M    M    M    M
SBB                    M    M    M    M    M    TM
SUB                    M    M    M    M    M    M
CMP                    M    M    M    M    M    M
CMPS                   M    M    M    M    M    M
SCAS                   M    M    M    M    M    M
NEG                    M    M    M    M    M    M
DEC                    M    M    M    M    M
INC                    M    M    M    M    M
IMUL                   M    --   --   --   --   M
MUL                    M    --   --   --   --   M
RCL/RCR 1              M                        TM
RCL/RCR count          --                       TM
ROL/ROR 1              M                        M
ROL/ROR count          --                       M
SAL/SAR/SHL/SHR 1      M    M    M    --   M    M
SAL/SAR/SHL/SHR count  --   M    M    --   M    M
SHLD/SHRD              --   M    M    --   M    M
BSF/BSR                --   --   M    --   --   --
BT/BTS/BTR/BTC         --   --   --   --   --   M
AND                    0    M    M    --   M    0
OR                     0    M    M    --   M    0
TEST                   0    M    M    --   M    0
XOR                    0    M    M    --   M    0