High-resolution graphics for the TRS-80
Unlike many competing computers, the TRS-80 Model I lacked any form of built-in high-resolution graphics. Although some TRS-80 compatible computers, such as the LNW80, offered high-resolution as a feature, the only graphics possible with the Model I were relatively low-resolution 128 by 48 block graphics. The many games written for the Model I made good use of these block graphics, and Radio Shack never made high-resolution a standard feature of the Model I, III, or 4. Several companies created products to address this deficiency, with some becoming more popular than others.
Model I
The Model I text screen was 64 by 16 characters with a character matrix of 6 by 12 pixels, meaning an underlying graphics resolution of 384 by 192. Although there were many “do-it-yourself” Model I high-resolution projects (such as the one detailed by Dennis Báthory-Kitsz in his book The Custom TRS-80), there were relatively few commercial products and they came fairly late in Model I development. The fact that the products were uncommon also meant that they enjoyed limited software support.
Name | Company | Date | Initial price | Resolution | Text overlay | Installation |
---|---|---|---|---|---|---|
80-GRAFIX | Programma International | 1980 | $149.95 | 384 by 192 (indirectly through character | not applicable | minimal soldering |
SubLOGIC 50/T80 | SubLOGIC | 1980 | unknown | 256 by 240 | no | plug-in |
E-RAM | Keyline Computer Products | 1980 | $349.95 | 256 by 192 | no | plug-in |
Mikeegraphic Graphic System | Mikee Electronics | 1981 | $340.00 | 384 by 192 | yes | soldering and trace cutting |
Color graphics for the Model I
The Model I, Model III, and Model 4 were all black and white computers. But there were a number of add-ons for the Model I that plugged into the expansion bus and displayed color text and graphics on an external monitor.
Name | Company | Date | Initial price | Maximum resolution | Maximum colors | Sprites |
---|---|---|---|---|---|---|
Electric Crayon | Percom | 1979 | $249.00 | 256 by 192 | 8 | no |
Color Graphics Interface | JFF Electronics | 1979 | $49.95 | 256 by 192 | 8 | no |
CHROMAtrs | South Shore Computer Concepts | 1982 | $169.00 | 256 by 192 | 16 | yes |
Color-Graf | Solectonics | 1982 | $260.00 | 256 by 192 | 16 | yes |
Mikrokolor | Andreasen’s Electronics Research & Development, Inc | 1983 | $235.00 | 256 by 192 | 16 | yes |
Micromint E-Z Color | Micromint | 1983 | $249.00 | 256 by 192 | 16 | yes |
Model III
Although the Model III text screen remained at 64 by 16 characters, the character matrix increased to 8 by 12 pixels. This meant that the graphics resolution also increased to 512 by 192. Radio Shack developed an “official” high-resolution add-on that used its own video controller to achieve higher resolution. Despite its official status, few programs supported it. Software support remained a problem for all of the add-ons: only the Grafyx Solution managed a significant number of compatible programs.
Name | Company | Date | Initial price | Resolution | Text overlay | Installation |
---|---|---|---|---|---|---|
80-GRAFIX | Micro-Labs | 1981 | $169.95 | 512 by 192 (indirectly through character redefinition) | not applicable | plug-in, with no soldering |
Mikeegraphic Graphic System | Mikee Electronics | 1982 | $340.00 | 512 by 192 | yes | soldering and trace cutting |
Grafyx Solution | Micro-Labs | 1982 | $299.95 | 512 by 192 | yes | plug-in and micro-clip connections |
Radio Shack High-Resolution Board | Radio Shack | 1982 | $369.95 | 640 by 240 | no | professional installation required |
Model 4
Unlike the Model I and III, the Model 4 was designed to support high-resolution even though it was never offered as a standard feature. The Model 4 motherboard had a built-in graphics connector to support a high-resolution add-on board. The Radio Shack Model 4 High-Resolution Board and the Model 4 Grafyx Solution were software compatible with each other (but not compatible with the Model III Grafyx Solution). This meant that most Model 4 high-resolution software worked with either board.
High-resolution add-ons (especially the Grafyx Solution) became a very popular item, and this led to a wide range of high-resolution programs being written for the Model 4.
Name | Company | Date | Initial price | Resolution | Text overlay | Installation |
---|---|---|---|---|---|---|
Radio Shack High-Resolution Board | Radio Shack | 1983 | $249.95 | 640 by 240 | possible using undocumented port | professional installation required |
Grafyx Solution | Micro-Labs | 1984 | $199.95 | 640 by 240 | yes | plug-in and micro-clip connections |
Mark McDougall says:
There was another Model I hires graphics board – the PCG-80. It allowed you to reprogram all 256 characters in the TRS-80 character set. For re-programming, it mapped the character memory into screen RAM, IIRC in 4 banks of 64 characters at a time.
I wrote a program that produced a lower case character set for our Model I. It was the first thing I ran each time I powered-on and booted NEWDOS/80. I also converted a few assembly language arcade games to hires, including Jungle Raiders and Star Cresta.
I have a copy of Jeff Vavasour’s Model I emulator that someone else patched for PCG-80 support. I did have these two games running on the emulator in the past. I also believe I have the documentation for the PCG-80 lying around somewhere too.
Mark McDougall says:
I just fired up the emulator again and found that there were a handful of other games converted to hires for this board, including ZChess, Sargon II, Hoppy, Black Hole, Star Bird & Time Trek. There was also a graphics basic and a program for editing characters.
David Sutherland says:
Perhaps just one additional chart could be added which would show: 1) all TRS-80 “clones” and 2) if any of the systems are compatible with each other the charts would show it.
Those charts are really good at quickly understanding what’s-what. Thanks again Matthew!