Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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     1     1
     8     5               7             0
    ┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
    │A│V│R│0│N│IO-│O│D│I│T│S│Z│0│A│0│P│1│C│◄── Layout of flags register
    │C│M│F│ │F│PL │F│F│F│F│F│F│ │F│ │F│ │F│
    └─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘
 
     Flag                  If set:
 
     CF    Carry           Carry or borrow to destination operand
     PF    Parity          Even parity in low-order byte of result
     AF    Aux. Carry      Carry or borrow to low four-order bits
     ZF    Zero            Result equal to 0
     SF    Sign            Result has negative sign
     TF    Trap            Switches to single-step mode
     IF    Interrupt       Enables interrupts (disables if cleared)
     DF    Direction       String operations process down rather than up
     OF    Overflow        Result too large or small for destination
     IOPL  I/O             I/O Privilege Level for IN, INS, OUT, OUTS,
           Priv                CLI, STI (286+)
     NF    Nested Task     Instruction caused nested task switch (286+)
     RF    Resume          Debug faults disabled during instruction
                           execution (386+)
     VM    Virtual 8086    Currently executing 8086 code on virtual
                           processor (386+)
     AC    Alignment       Data aligned to four-byte boundary (486+)
           Check
 
     See also: Processor Registers Summary, Coprocessor Status Word,
               Coprocessor Control Word, Coprocessor Environment
                                    -♦-