SofaSMS and Franky: Screen Corruption

By jdgabbard

Resident (44)

jdgabbard's picture

25-07-2022, 18:38

I'm not sure if this issue is hardware related or software patching related...

I just finished building my Franky v1.1, and the board seems to work. I have played a few games that seem to function without any issues, such as Alex Kidd. However, I noticing that some games suffer from screen corruption. Though I cannot pin down if this is an issue with the VDP, the SRAM, or possibly the software patching process in SofaSMS v1.0.

I've added a video so that you can see what I am seeing. In the video it starts at about the 30 second mark. Though, the reason I suspect this may be an issue with the patching routine is that the sound seems off in this game. It does not sound unusual in other games. I cannot be certain, I did check all of the components used on the board with the exception of the VDP, SRAM and all 7400 ICs are good. So I suppose it could be a problematic VDP. However, it doesn't explain why some games do not have this issue, and others do.

Video Here

The game in question is Aliens 3. I've also noted that in Phantasy Star when going through dungeons or in combat the lower 40% of the screen is also corrupted. This seems to be a problem with larger games. And I'm guessing it might possibly be something to do with the difference in how the mappers for the SMS and MSX work. Other games do seem to load, but then never seem to execute. So I'm leaning towards this being a problem with certain games in SofaSMS.

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