User's Manual

THE 80286 INSTRUCTION SET
INS/INSB/INSW-Input from Port to String
Opcode
6C
60
6C
60
FLAGS MODIFIED
None
Instruction
INS eb,OX
INS ew,OX
INSB
INSW
FLAGS UNDEFINED
None
OPERATION
Clocks
5
5
5
5
Description
Input byte from port OX into ES:[OI)
Input
word from port OX into ES:[OI)
Input
byte from port OX into ES:[OI)
Input
word from port OX into ES:[OI)
INS transfers data from the input port numbered by the DX register to the memory byte or word at
ES:DI. The memory operand must be addressable from the ES register; no segment override is
possible.
INS does not allow the specification of the port number as an immediate value. The port must be
addressed through the DX register.
After the transfer
is made, DI is automatically advanced. If the direction flag is 0 (CLD was executed),
DI increments;
if the direction flag is 1 (STD was executed), DI decrements. DI increments or decre-
ments by
1 if a byte was moved; by 2 if a word was moved.
INS can be preceded by the REP prefix for block input of CX bytes or words. Refer to the REP
instruction for details of this operation.
Intel has reserved
I/O port addresses 00F8H through OOFFH; they should not be used.
NOTE
Not all input port devices can handle the rate at which this instruction transfers input
data
to memory.
PROTECTED MODE EXCEPTIONS
#GP(O) if CPL > 10PL. #GP(O) if the destination is in a non-writable segment. #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
Interrupt 13 for a word operand at offset OFFFFH.
B-47