Intel 80C188XL, 80C186XL user manual Instruction Set Descriptions, Table C-3.Flag Bit Functions

Models: 80C186XL 80C188XL

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Table C-3. Flag Bit Functions

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.

 

 

C-3

Page 326
Image 326
Intel 80C188XL, 80C186XL user manual Instruction Set Descriptions, Table C-3.Flag Bit Functions