1. Introduction

This HOWTO document describes programming hardware I/O ports and waiting for small periods of time in user-mode Linux programs running on the Intel x86 architecture. This document is a descendant of the very small IO-Port mini-HOWTO by the same author.

This document is Copyright 1995-1997 Riku Saikkonen. See the Linux HOWTO copyright for details.

If you have corrections or something to add, feel free to e-mail me (Riku.Saikkonen@hut.fi)...

Changes from the previous released version (Mar 30 1997):

• Clarified things regarding inb_p/outb_p and port 0x80.
• Removed information about udelay(), since nanosleep() provides a cleaner way of using it.
• Converted to Linuxdoc-SGML, and reorganised somewhat.
• Lots of minor additions and modifications.