Intel 80286, 80287 manual PUSH-Push a Word onto the Stack, Push CS, Push SS, Push DS

THE 80286 INSTRUCTION SET

PUSH-Push a Word onto the Stack

Opcode		Instruction		Clocks	Description
06		PUSH	ES	3	Push ES
OE		PUSH CS		3	Push CS
16		PUSH SS		3	Push SS
1E		PUSH DS		3	Push DS
50+ rw		PUSH	rw	3	Push word register
FF	/6	PUSH	mw	5	Push memory word
68	dw	PUSH	dw	3	Push immediate word
6A	db	PUSH	db	3	Push immediate sign-extended byte

FLAGS MODIFIED

None

FLAGS UNDEFINED

None

OPERATION

The stack pointer SP is decremented by 2, and the operand is placed on the new top of stack, which is pointed to by SS:SP.

The 80286 PUSH SP instruction pushes the value of SP as it existed before the instruction. This differs from the 8086, which pushes the new (decremented by 2) value.

PROTECTED MODE EXCEPTIONS

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

#GP(O) for an illegal memory operand effective address in the CS, DS, or ES segments; #SS(O) for an illegal address in the SS segment.

REAL ADDRESS MODE EXCEPTIONS

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

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