Summary

12" monochrome monitor by Atari, introduced with their ST line of computers in 1985. Supports the ST's high-resolution monochrome mode of 640x400p at 71.25hz. Originally manufactured by GoldStar in Korea.

(Special thanks to Josh Olthoff for the pics!)

Manuals

• Owner's Manual (Euro model)
• Service Manual (Euro model)
• Schematics

Notes

There were two design variants. This model is the first, chassis MT-9, and the the second chassis was MT-21. However, there are multiple revisions of the chassis with differing parts as well. This article goes over them.

The displayed raster on these monitors is notorious for being rather small. (This was done to maintain consistency with direct-to-print size.) While you can stretch the raster to fill up more of the screen using the internal potentiometers, this may cause premature failure of internal components due to running the monitor beyond its tolerances.

Fortunately, there is a solution. By replacing a capacitor on the chassis with higher specs, you can safely run the monitor with the raster filling up the screen. Watch this video to learn more: Atari SM124 monitor mods