Table c3. flag bit functions – Intel 80C188XL User Manual

Page 326

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C-3

INSTRUCTION SET DESCRIPTIONS

Table C-3. Flag Bit Functions

Name

Function

AF

Auxiliary Flag:

Set on carry from or borrow to the low order four bits of AL; cleared otherwise.

CF

Carry Flag:

Set on high-order bit carry or borrow; cleared otherwise.

DF

Direction Flag:

Causes string instructions to auto decrement the appropriate index register
when set. Clearing DF causes auto increment.

IF

Interrupt-enable Flag:

When set, maskable interrupts will cause the CPU to transfer control to an
interrupt vector specified location.

OF

Overflow Flag:

Set if the signed result cannot be expressed within the number of bits in the
destination operand; cleared otherwise.

PF

Parity Flag:

Set if low-order 8 bits of result contain an even number of 1 bits; cleared
otherwise.

SF

Sign Flag:

Set equal to high-order bit of result (0 if positive, 1 if negative).

TF

Single Step Flag:

Once set, a single step interrupt occurs after the next instruction executes. TF
is cleared by the single step interrupt.

ZF

Zero Flag:

Set if result is zero; cleared otherwise.

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