“SuperCGA” and ATI Graphics Solution and GEM Desktop
8bit guy published a video
about SuperCGA cards, which reminded me that this was a topic a
recently dug into. I’ve never really worked with CGA/EGA monitors. When
we had a computer at home for the first time in 1989, it was an IBM PS/2
Model 20 borrowed from dad’s office. That computer already had an
on-board graphics chip that worked with VGA monitors. One year later, my
family decided to buy our own computer. It was a 286 clone with an SVGA
graphics card and an SVGA monitor able to show 1024×768 (interlaced
though).
During the Bytefest (a vintage computer show in Czech Republic), one
of the computers I brought there was an early Vienna 286. A friend of
mine promised that he would have brought an EGA monitor, so I could try a
card I bought just for this purpose – a Trident 8800CS (512KB). This
Trident has both VGA and RGBI/TTL (CGA/EGA) outputs and can be switched
to act like different IBM graphics chips. Sadly, the Trident card was
ignoring the switches and always used VGA timing. It sent the signal
always to both outputs but my EGA monitor was not able to sync 640×480
with 31kHz h-sync (as expected). We brought an oscilloscope, even made
some modifications to the card, but nothing helped. When I asked in some
groups, the only answer I got was that somebody tried the same thing on
his Trident 8800CS with the same result.
Anyway, I also had the original ATI Graphics Solution card that was
sold with the computer somewhere in 1987, so at least I had something
else to play with. This is a very neat card. It has 64KB of video RAM
and supports both CGA and Hercules modes. As I shown in the past, it
even supports CGA modes on Hercules/MDA monitors
using clever timing tricks. The card was used in the Hercules mode for
the whole its life as the machine served in an electrical engineering
lab for designing electric circuits. This was finally the time for me to
switch it into the native CGA mode.
Seeing the CGA modes was not so interesting for me. However, the card
supports also non-standard modes that can utilize the whole memory
which is four times of what the IBM CGA has. The obvious choice was
something that supports Plantronics ColorPlus which ATI supported like
many other CGA-clone vendors. Yes, I tried Planet-X3 and Space Quest 3
in 320×200 with 16 colors. However, Planet-X3 is a modern game, and the
Space Quest 3 uses a modern video driver to support this card (the
original game did not have it). I was more interested in productivity
apps. After seeing that GEM Desktop (sort of a Windows competitor)
provides support for ColorPlus, I installed the whole bundle.
At the beginning, everything looked just like with CGA – black &
white only. This was because the desktop environment does not use more
colors there. On the other side, if I moved the mouse fast enough, it
was visible that sometimes the cursor was ping instead of black for a
moment. Thus, I knew that we were actually in the 4-color mode. After
installing office programs, I was finally able to see all four colors in
640×200. Quickly after that I realized that among desktop accessories,
there is a calculator that uses magenta as a background color. Anyway, I
am happy that I also tried these office/productivity apps. From my
point of view, they are gimmick. They look like they support everything
but when you try to do something, you get the feeling that they were
designed more to present the functionality of the desktop environment.
The ColorPlus had just 32KB of video RAM and my ATI Graphics Solution
has 64KB, so it should be able to drive 640×200 in full 16 colors. I’ve
checked the user guide for the card and indeed this mode was mentioned
there. ATI manual says that there is support for it in AutoCAD, PC
Paintbrush+, Lotus 1-2-3, Symphony and Framework II. I installed the PC
Paintbrush+ as a bitmap editor can benefit the most from such a mode.
The support for this card was built in the software so no extra drivers
were needed. After selecting the mode, I was able to get the best out of
a CGA 200-line monitor. What I really like, the bundled ATI driver disk
contains a small example program to enable this mode (including its
source code), so programmers could modify their own programs to get more
than what a standard CGA offered.
Original article with hi-res photos: here