The Model 4 Grafyx Solution

written by Matthew Reed

The Model 4 Grafyx Solution was the most popular high-resolution add-on for the TRS-80 Model 4, and probably the most popular Model 4 add-on in general. It was introduced in 1984 for a price of $199.95 by Micro-Labs, creators of the earlier Model III Grafyx Solution. The Model 4 Grafyx Solution provided true high-resolution access to every pixel on the 640 by 240 Model 4 display, yet was easily user-installable in only a few minutes.

Micro-Labs advertisement for the Model 4 Grafyx Solution

Micro-Labs advertisement from the August 1984 issue of 80 Micro>

Unlike the memory mapped Model III Grafyx Solution, the Model 4 Grafyx Solution was port-mapped. It used the same ports and mapping as the Radio Shack Model 4 high-resolution board. This meant that the Model 4 Grafyx Solution was almost completely compatible with the Radio Shack board and they could run the same programs. This had the odd side effect of making the Model 4 Grafyx Solution in Model III mode incompatible with the Model III Grafyx Solution.

The Model 4 Grafyx Solution had many advantages compared to the Radio Shack board:

  • It was about 25% faster writing to the screen.
  • It could display both text and graphics at the same time. The Radio Shack board did have a way to display both, but the method was undocumented and rarely used.
  • It was much cheaper and could be easily installed by the user.

It also had a few disadvantages compared to the Radio Shack board:

  • It had only 20K of graphics memory instead of 32K (only 19K was required to store the graphics screen).
  • It had no way to turn off wait states, which could potentially increase graphics speed at the expense of screen hash.
  • It didn’t support the undocumented display offset features that were sometimes used for hardware scrolling.

Those disadvantages tended not to be very important in practice because only a handful of programs supported the extra features of the Radio Shack board.


Like the Model III Grafyx Solution, the Model 4 version came with an excellent enhanced graphics BASIC called GBASIC. This BASIC, though not syntax compatible with the BASICG bundled with the Radio Shack high-resolution board, was considered to be far superior by most users. Most freeware and commercial high-resolution BASIC programs would only work with GBASIC, not BASICG. Micro-Labs sold a special version of GBASIC designed specifically for owners of the Radio Shack high-resolution board so that they could use these programs.

There were dozens of high-resolution programs available for the Model 4 Grafyx Solution, both freeware and commercial. Some notable examples include:

  • MDRAW, a freeware drawing program by Scott McBurney and Gary Shanafelt
  • MagicDraw, a paint program by David Goben
  • GIF4MOD4, a GIF viewer by J.F.R. “Frank” Slinkman
  • xT.CAD, computer aided drafting software by Microdex Corporation
  • Tournament Chess by Rapidynamic Software


Although Micro-Labs moved on to other platforms, they maintained a presence in the TRS-80 world long after most other companies had left. Micro-Labs president Ted Carter stated in 1988 that “We will continue to support the TRS-80 as long as there is anyone out there.” The Grafyx Solution was one of the last hardware products to be sold for the Model 4.

The price of the Grafyx Solution was reduced to $149.95 in 1988 and then to $99.95 in 1992. Computer News 80 took over distribution of the Grafyx Solution from Micro-Labs in 1992. They continued to sell Grafyx Solution boards as late as 2004.

In 2015, Ian Mavric introduced a new high-resolution board for the Model 4 that is hardware compatible with the Grafyx Solution and its software. You can find out more on his high-resolution graphics page.

Categories: Graphics, Hardware