Re: Linux Post codes during runtime, possibly OT

From: Rogier Wolff (R.E.Wolff@BitWizard.nl)
Date: Sat Jan 27 2001 - 05:20:04 EST

H. Peter Anvin wrote:
> Followup to: <3A709E99.25ADE5F6@echostar.com>
> By author: "Ian S. Nelson" <ian.nelson@echostar.com>
> In newsgroup: linux.dev.kernel
> >
> > I'm curious. Why does Linux make that friendly 98/9a/88 looking
> > postcode pattern when it's running? DOS and DOS95 don't do that.
> >
> > I'm begining to feel like I can tell the system health by observing it,
> > kind of like "seeing the matrix."
 
> It output garbage to the 80h port in order to enforce I/O delays.
> It's one of the safe ports to issue outs to.

Yes, because it is reserved for POST codes. You can get "POST
debugging cards" that simply have a BIN -> 7segement encoder and two 7
segment displays on them. They decode 0x80. That's what it's for.

Roger. 

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
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