Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!rpi!masscomp!peora!tarpit!bilver!jwt!john
From: john@jwt.UUCP (John Temples)
Newsgroups: comp.unix.sysv386
Subject: Re: Need to Address i/o ports directoly HELP!!
Message-ID: <1991Feb14.230855.4613@jwt.UUCP>
Date: 14 Feb 91 23:08:55 GMT
References: <1991Feb14.044524.3106@grebyn.com>
Organization: Private System -- Orlando, FL
Lines: 23

In article <1991Feb14.044524.3106@grebyn.com> yml@grebyn.UUCP (Yermo M. Lamers) writes:
>In the SCO unix manuals they described a system for directly accessing
>the video boards (EGA, VGA and the like). Is there a way without writing
>a device driver to write/read bytes to/from an I/O port?  Has anyone out
>there already solved a similar problem?

ISC and ESIX have ioctl calls documented in display(7): KDADDIO,
KDENABIO, and  MCAIO, though I've never tried using these with
arbitrary addresses not on the video cards.  I just wrote a one-line
device driver:

u.u_ar0[EFL] |= PS_IOPL;

which, when opened, gives you I/O privilege level so you can
read/write any port.  This comes in handy for lots of different
things, like reprogramming keyboard repeat rates, or doing quick-hack
hardware interfaces like you've described above.  Note that this does
subvert some of the OS's protection; use at your own risk, etc.

Of course, on ISC/ESIX, the above doesn't need to be in a device
driver since the u block is writeable.  :(
-- 
John W. Temples -- john@jwt.UUCP (uunet!jwt!john)