💾 Archived View for uscoffings.net › retro-computing › systems › Tandy › oldskool › vgafix.txt captured on 2023-07-10 at 15:14:13.
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Subject: Problems with VGA
Fm: GAVIN LENNOX 76535,3062
I HAVE A 1000TX WITH VGA ALOT OF SOFTWARE WILL NOT
RECOGNIZE MY VGA CAN ANYONE HELP???
Fm: Tommy Bevins 76510,1526
I had the same problem with my 1000TL. It seems Tandy has an error in its
BIOS that screws up programs that try to autosense the video mode. An article
in the magazine One Thousand provided a fix for this.
The fix to the problem is to change the value of the byte at 0000:048A
from 3F to the correct value. The correct values are listed in Table #3.
Until Tandy comes up with a fix to their BIOS, the following program written
by ATI will solve the problem:
Using DEBUG.COM from you Disk Operating System, type the instructions
in Figure #4 to create a short executable file called T1KVGA.COM. Put the
value from Table #3 that matches the set up of your computer in where the "__"
is shown. For almost all users, the value will be "0B".
Run this program every time you boot the computer and want to use
software that auto-detects your VGA card.
Table #3: Fix Values
---------------------
Default Video Mode Value Meaning
--------------------- --------- --------------------------------
VGA color 0B single VGA color display
VGA color and MDA 0C dual monitors with VGA
color and mono text boards
VGA mono 0D single VGA monochrome display
VGA mono and CGA 0E dual monitors with VGA mono
and CGA color boards
Figure #4: T1KVGA.COM Listing
------------------------------
C:> DEBUG
E 100
B8 00 00 8E D8 B0 __ 3E A2 8A 04 B8 00 4C CD 21
RCX
0010
NT1KVGA.COM
W
Q
I typed this in and substituted the 0B for the "__" in the listing. This fixed
problems that I had encountered when trying to run software that tried to
auto-detect the video modes.
-Tommy