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This HTML version of the file intel.doc from the
PC Game Programmer's guide was produced by Zack T Smith. Fancy HTML modifications are copyright ©
2005 by Zack T Smith, all rights reserved.
This information is provided in the hope that it will be useful,
but without any warranty. It is provided AS-IS,
without even the implied warranty of fitness for a particular purpose.
P Instructions
POP - Pop Word off Stack
Usage: POP dest
Modifies flags: None
Transfers word at the current stack top (SS:SP) to the destination
then increments SP by two to point to the new stack top. CS is not
a valid destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 8 5 4 4 1
reg32 4 - - 4 1
segreg 8 5 7 3 1
mem16 17+EA 5 5 6 2-4
mem32 5 - - 6 2-4
POPA/POPAD - Pop All Registers onto Stack (80188+)
Usage: POPA
POPAD (386+)
Modifies flags: None
Pops the top 8 words off the stack into the 8 general purpose 16/32
bit registers. Registers are popped in the following order: (E)DI,
(E)SI, (E)BP, (E)SP, (E)DX, (E)CX and (E)AX. The (E)SP value popped
from the stack is actually discarded.
Clocks Size
Operands 808x 286 386 486 Bytes
none - 19 24 9 1
POPF/POPFD - Pop Flags off Stack
Usage: POPF
POPFD (386+)
Modifies flags: all flags
Pops word/doubleword from stack into the Flags Register and then
increments SP by 2 (for POPF) or 4 (for POPFD).
Clocks Size
Operands 808x 286 386 486 Bytes
none 8/12 5 5 9 1 (W88=12)
none (PM) - - 5 6 1
PUSH - Push Word onto Stack
Usage: PUSH src
PUSH immed (80188+ only)
Modifies flags: None
Decrements SP by the size of the operand (two or four, byte values
are sign extended) and transfers one word from source to the stack
top (SS:SP).
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 11/15 3 2 1 1
reg32 - - 2 1 1
mem16 16+EA 5 5 4 2-4 (W88=24+EA)
mem32 - - 5 4 2-4
segreg 10/14 3 2 3 1
immed - 3 2 1 2-3
PUSHA/PUSHAD - Push All Registers onto Stack (80188+)
Usage: PUSHA
PUSHAD (386+)
Modifies flags: None
Pushes all general purpose registers onto the stack in the following
order: (E)AX, (E)CX, (E)DX, (E)BX, (E)SP, (E)BP, (E)SI, (E)DI. The
value of SP is the value before the actual push of SP.
Clocks Size
Operands 808x 286 386 486 Bytes
none - 19 24 11 1
PUSHF/PUSHFD - Push Flags onto Stack
Usage: PUSHF
PUSHFD (386+)
Modifies flags: None
Transfers the Flags Register onto the stack. PUSHF saves a 16 bit
value while PUSHFD saves a 32 bit value.
Clocks Size
Operands 808x 286 386 486 Bytes
none 10/14 3 4 4 1
none (PM) - - 4 3 1
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