Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!sco!loranb
From: loranb@sco.COM (Loran Ball)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Super VGA Standard
Keywords: VGA
Message-ID: <3464@scolex.sco.COM>
Date: 20 Oct 89 18:37:51 GMT
References: <3458@scolex.sco.COM> <9777@attctc.Dallas.TX.US>
Reply-To: loranb@sco.COM (Loran Ball)
Organization: The Santa Cruz Operation, Inc.
Lines: 21

In article <9777@attctc.Dallas.TX.US> chasm@attctc.Dallas.TX.US (Charles Marslett) writes:
>One major feature that I hope makes it through is the ability to use some
>parts of the BIOS in protected mode (without the overhead of ABIOS) -- this
>may make support of higher resolution graphics modes more board independent
>in future versions of Xenix, et al.  (The procedure involves optional copying
>of small blocks of code from the BIOS into the executable code segment of the
>operating system, so changing the card results in changing the code.)

Besides running in protected mode, BIOS must be re-entrant for Xenix to
use it.  Xenix doesn't use any BIOS provided on PC/AT motherboards
or expansion boards.  We can do this because the hardware is all standardized
at the register level.

I'm not a member of VEGA, but the only way I can envision the new BIOS
standard supporting DOS and Xenix/Unix environments properly is to have
two versions of it on the VGA adapter.  A non-reentrant, real mode version
for DOS and a reentrant, protected mode version for Xenix/Unix.

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Loran Ball (loranb)		uunet!sco!loranb	loranb@sco.COM
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