From owner-freebsd-questions  Wed Nov 15 06:12:57 1995
Return-Path: owner-questions
Received: (from root@localhost)
          by freefall.freebsd.org (8.6.12/8.6.6) id GAA00907
          for questions-outgoing; Wed, 15 Nov 1995 06:12:57 -0800
Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19])
          by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id GAA00754
          ; Wed, 15 Nov 1995 06:11:33 -0800
Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id AAA04591; Thu, 16 Nov 1995 00:06:23 +1100
Date: Thu, 16 Nov 1995 00:06:23 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199511151306.AAA04591@godzilla.zeta.org.au>
To: darrylo@hpnmhjw.sr.hp.com, freebsd-bugs@freebsd.org,
        freebsd-questions@freebsd.org
Subject: Re: "Bug" in syscons?
Sender: owner-questions@freebsd.org
Precedence: bulk

>which solves my corrupt font problems with syscons.  Can anyone tell me
>what the old 2.0.5 syscons is trying to do with the "weird" VGA register
>values?  I know what my "fixed" values are doing, but what are the old
>values trying to do?  (I just ordered a copy of Richard Wilton's
>"Programmer's Guide to PC Video Systems", but it hasn't arrived yet.)

In set_font_mode():
old:
>      outb(TSIDX, 0x02); outb(TSREG, 0x04);
>!     outb(TSIDX, 0x04); outb(TSREG, 0x06);
>      outb(GDCIDX, 0x04); outb(GDCREG, 0x02);
>      outb(GDCIDX, 0x05); outb(GDCREG, 0x00);
>!     outb(GDCIDX, 0x06); outb(GDCREG, 0x05);
new:
>      outb(TSIDX, 0x02); outb(TSREG, 0x04);
>!     outb(TSIDX, 0x04); outb(TSREG, 0x07);
>      outb(GDCIDX, 0x04); outb(GDCREG, 0x02);
>      outb(GDCIDX, 0x05); outb(GDCREG, 0x00);
>!     outb(GDCIDX, 0x06); outb(GDCREG, 0x00);

TS reg 4 bit 0x01 is "Reserved" for the ET4000.  Better not use it.
GDC reg 6 bit 0x01 is "Graphics mode enable"; bits 0x04 and 0x08
select the memory map:
	0x00: 128K at 0xA0000
	0x04:  64K at 0xA0000
	0x08:  32K at 0xB0000
	0x0C:  32K at 0xB8000

Bruce