Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!husc6!mit-eddie!genrad!decvax!dartvax!vizard
From: vizard@dartvax.UUCP (Todd Krein)
Newsgroups: comp.os.minix
Subject: Re: Request for help with EGA board fix posted by Der-Ru Sheu
Message-ID: <6476@dartvax.UUCP>
Date: Mon, 15-Jun-87 16:22:53 EDT
Article-I.D.: dartvax.6476
Posted: Mon Jun 15 16:22:53 1987
Date-Received: Sun, 21-Jun-87 06:02:08 EDT
References: <1207@botter.cs.vu.nl>
Organization: Dartmouth College, Hanover, NH
Lines: 25
Summary: Not with Tseng labs...

In article <1207@botter.cs.vu.nl>, ast@cs.vu.nl (Andy Tanenbaum) writes:
> A while back sheu@gitpyr.UUCP (Der-Ru Sheu) posted the following fix
> to make the EGA board work:
> 
>  > Following is a brief explanation.  There is a register inside the EGA 
>  > sequencer, to tell 'Extended Memory' (those beyond 64K, or 16K in fact, 
>  > since 4 color planes share the same memory space) is installed or not.  
>  > By cheating the hardware no extended memory installed, it will perform
>  > exactly like a CGA (but with a much better resolution, of course).
>  > 
>  >   port_out(0x3c4, 4);   /* Select register inside the sequencer     */
>  >   port_out(0x3c5, 1);   /* No extended memory, take my word for it. */
>  > 
> We finally tried it here and it didn't quite work.  However, we tried it on a
> Zenith Z-248 EGA card, which may be different from IBM's.  Since it is

	I just got an NEC GB-1 (or a renamed EVA-480). This nice fix won't
work on it, or any board using Tseng Labs chips, as this implementation
doesn't have a comparable register. If you do have such a board, you'll
have to use the new scrolling routines that someone (I don't remember his
name) posted to fix it. I've installed them, and thay work great. (Snaps
to that nameless author). Perhaps this is the problem...

	Todd Krein
	vizard@dartvax