Path: utzoo!attcan!uunet!pcrat!rick
From: rick@pcrat.UUCP (Rick Richardson)
Newsgroups: comp.unix.xenix
Subject: Re: VPIX Problems/Questions...
Message-ID: <644@pcrat.UUCP>
Date: 13 Jan 89 15:00:17 GMT
References: <5980001@hplsla.HP.COM> <5980002@hplsla.HP.COM> <401@ispi.UUCP>
Reply-To: rick@pcrat.UUCP (Rick Richardson)
Organization: PC Research, Inc., Tinton Falls, NJ
Lines: 27

In article <401@ispi.UUCP> jbayer@ispi.UUCP (Jonathan Bayer) writes:
>In article <5980002@hplsla.HP.COM> jeffh@hplsla.HP.COM (Jeff Harrell) writes:
>>You mean VPIX is not resetting the graphics mode...
>
>No. I meant what I said.  VP/ix can't get all the proper info from the
>card, therefore if you leave it in an unknown state it doesn't know
>about it, either the way it was, or the way it is.

Actually, one would think that all I/O to the registers are trapped by the
kernel.  This makes it possible to know exactly what state even the
write-only registers are in.  Whether or not this is being done
thoroughly is a question I can not answer.

However, the problem *may* not be VP/ix but rather the virtual terminals.
The following is specific to ISC's 386/ix, but the problems to be solved
are non-trivial and I could easily see SCO running into the same troubles.
I've noticed, on rare occasion, that regular UNIX programs that put
a virtual terminal into a graphics mode can also exhibit the problem
where switching out and then back leaves the screen blank.  This doesn't
happen very often, but I've seen it with X-windows and with
graphics programs written here that tweek EGA registers.

-- 
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