Hi guys,

I need expert opinion to figure out how to get MDA display to work with the OSSC to HDMI on a modern display.

I built a simple cable that brings down TTL to VGA voltages, and also built Necroware's MCE adapter. Both converters were able to get CGA/EGA display to successfully show on a modern display when they are fed to the OSSC for upscaling via the VGA input (of course my simple cable doesn't have the brown fix, but that's irrelevant here).

The next step is MDA. Now both my simple cable and the MCE adapter cause the OSSC to go crazy. It keeps trying to sync to a signal, and its LCD status display keeps cycling very quickly between 18KHz and 32KHz and "No input".

I tried a pure MDA card, and an EGA card set to MDA mode, and they both cause the same behavior on the OSSC. I tried playing with all Sync and Sampling options of the OSSC, but nothing helped.

What's so special about MDA other than 18KHz? Or is 18KHz a cursed frequency on the OSSC? 😅 The OSSC is definitely capable of 15.75KHz and 31.5KHz, so I doubt 18.432KHz is "too hard" for the OSSC.

Any theories?