Intel 80286, 80287 manual PUSHF-Push Flags Register onto the Stack, Push flag~ register, Pushf

THE 80286 INSTRUCTION SET

PUSHF-Push Flags Register onto the Stack

Opcode Instruction ClocksDescription

9C PUSHF 3 Push flag~ register

FLAGS MODIFIED

None

FLAGS UNDEFINED

None

OPERATION

The stack pointer SP is decremented by 2, and the 80286 flags register is copied to the new top of stack, which is pointed to by SS:SP. The flags, from the top bit (15) to the bottom bit (0), are as follows: undefined, nested task, I/O privilege level (2 bits), overflow, direction, interrupts enabled, trap, sign, zero, undefined, auxiliary carry, undefined, parity, undefined, and carry.

PROTECTED MODE EXCEPTIONS

#SS(O) if the new value of SP is outside the stack segment limit.

REAL ADDRESS MODE EXCEPTIONS

None; the 80286 will shut down if SP= I due-to lack of stack space.

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