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C-33
INSTRUCTION SET DESCRIPTIONS
OUTS Out String:
OUTS
port, src_string
Performs block output from memory to
an I/O port. The port address is placed
in the DX register. The memory
address is placed in the SI register.
This instruction uses the DS segment
register, but this may be changed with
a segment override instruction. After
the data transfer takes place, the
pointer register (SI) increments or
decrements, depending on the value
of the direction flag (DF). The pointer
register changes by 1 for byte
transfers or 2 for word transfers.
Instruction Operands:
OUTS port, src_string
OUTS (repeat) port, src_string
(dst) ← (src) AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
POP Pop:
POP
dest
Transfers the word at the current top of
stack (pointed to by SP) to the
destination operand and then
increments SP by two to point to the
new top of stack.
Instruction Operands:
POP reg
POP seg-reg (CS illegal)
POP mem
(dest) ← ((SP) + 1:(SP))
(SP) ← (SP) + 2
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