Graphics are garbled in 15Khz TVs (but CGA was 15KHz-compatible)

[vanfanel]

Hi there,

I have been trying to make the MiSTer PCXT core, which uses this Graphics Gremlin module, working on a CRT TV (15KHz). My understanding is that original CGA cards were 15KHz compatible since so many DOS games use the composite artifacting to their advantage.

However, only text mode seems to work: as soon as a CGA game is launched, graphics are garbled in all 15KHz displays I have tried.

So, would it be possible to have 15KHz support added to the Graphics Gremlin module, please?