Online HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens
IN - Input Byte or Word From Port
Usage: IN accum,port
Modifies flags: None
A byte, word or dword is read from "port" and placed in AL, AX or
EAX respectively. If the port number is in the range of 0-255
it can be specified as an immediate, otherwise the port number
must be specified in DX. Valid port ranges on the PC are 0-1024,
though values through 65535 may be specified and recognized by
third party vendors and PS/2's.
Clocks Size
Operands 808x 286 386 486 Bytes
accum,immed8 10/14 5 12 14 2
accum,immed8 (PM) 6/26 8/28/27 2
accum,DX 8/12 5 13 14 1
accum,DX (PM) 7/27 8/28/27 1
- 386+ protected mode timings depend on privilege levels.
first number is the timing if: CPL >= IOPL
second number is the timing if: CPL > IOPL or in VM 86 mode (386)
CPL <= IOPL (486)
third number is the timing when: virtual mode on 486 processor
- 486 virtual mode always requires 27 cycles
- see Instruction Timing
[helppc.bosbyte.nl] in