Re: [PARPORT] Can I...

David Campbell (
Thu, 22 Oct 1998 14:51:31 +0800

Date sent: Thu, 22 Oct 1998 01:38:41 -0400
From: Keith Baker <>
Subject: [PARPORT] Can I...

> I have a small Parallel port -> DMX (A stage lighting protocol) converter.
> I would like to write software for it under linux. I need to be able to read
> and write to the || port pins... I think the paper out pin for example. I
> guess if I understand correctly root could do this with a simple write to that
> io address... But I want to be able to run it as an ordinary user... How
> would I go about it?

#include <asm/io.h>

for inb(), outb()

You will need to call iopl() first to grant root access to io registers. Remeber
to compile with -O2 as the inb/out functions are macros which do not fully
unwind themselves (sometimes left as extern calls when they are inlines).

If you really want to see an example bit of code that toys with the parallel
port, grab and take a good
look at the file id_probe.c in the common sub-directory (after you expand the
tgz file).

David Campbell

Current project list:
a) Maintain Linux ZIP drivers (documentation needed)
b) Create Linux chipset specific parport drivers

Any assistance to clearing this list most welcome

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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:18:39 EST