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INSTRUCTION SET DESCRIPTIONS
C-34
POPA Pop All:
POPA
Pops all data, pointer, and index
registers off of the stack. The SP value
popped is discarded.
Instruction Operands:
none
(DI) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(SI) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(BP) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(BX) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(DX) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(CX) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
(AX) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
POPF Pop Flags:
POPF
Transfers specific bits from the word at
the current top of stack (pointed to by
register SP) into the 8086/8088 flags,
replacing whatever values the flags
previously contained. SP is then
incremented by two to point to the new
top of stack.
Instruction Operands:
none
Flags ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
AF
CF
DF
IF
OF
PF
SF
TF
ZF
PUSH Push:
PUSH
src
Decrements SP by two and then
transfers a word from the source
operand to the top of stack now
pointed to by SP.
Instruction Operands:
PUSH reg
PUSH seg-reg (CS legal)
PUSH mem
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (src)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
Table C-4. Instruction Set (Continued)
Name Description Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
the flag is updated after the instruction is executed