To:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Re: 16.7M color driver for ET4000
References:	<9301021344 DOT aa01707 AT rubble DOT UUCP>
Date:	Mon, 04 Jan 93 12:56:50 -0800
From:	Peter Kaminski <kaminski AT netcom DOT com>

In message <9301021344 DOT aa01707 AT rubble DOT UUCP>, Chris Nitsopoulos <chris AT rubble>
writes:

>In the process of upgrading to a new computer, I installed a 
>ET4000 local bus card with a ATT20C491 RAMDAC that is capable
>of displaying 16.7M colors at 640x480.  Unfortunatly the supplied
>ET4000 driver in the djgpp package no longer works in Hicolor mode.  

If your RAMDAC is still Sierra-compatible, it may be that the driver
just doesn't know it, and is refusing to do HiColor -- that's the
problem I had with my Renoir Ultra SVGA.  The ET4000.GRN (I assume
you're using libgrx) driver checks for a RAMDAC with this code:

driver_init_routine     proc    far
        mov     ax,10f1h                ; get DAC type
        int     10h
        cmp     ax,10h
        jne     no_HiColor
        cmp     bl,1
        je      have_HiColor

The (sketchy) docs I have for the Tseng BIOS say:

----------1010F1-----------------------------
INT 10 - VIDEO - Tseng ET-4000 BIOS - GET DAC TYPE
        AX = 10F1h
Return: AX = 0010h if succesful, errorcode if not
        BL = type of digital/analog converter
             00h normal VGA DAC
             01h Sierra SC1148x HiColor DAC
             else other HiColor DAC
SeeAlso: AX=10F0h

My card returns a "4" for type of RAMDAC instead of a "1".  I'm not sure
what RAMDAC it is, but it must not be a Sierra SC1148x.

Anyway, if that's your only problem you can just patch the driver.  I
didn't have an assembler handy, so I patched the binary -- at offset
0x120, changing 0x01 0x74 to 0x00 0x75 changes it from checking for
"equals 1" to "not equals 0", and made it work for me.

Good luck!

Pete

- Raw text -