Samurai Shodown unplayble demo on MSX+V9990

thanks, your videos confirm my suspicions, my Vram is broken.

In the mean time I also tested on my Sony MSX2+, which gave similar results for both roms. I'm also experimentnig with my own game for V9990 (based on a UBox MSX1 library conversion for V9990 which I made), but also there I do see some artefacts (and especially some problems with the sprites, it often ends up with a lot of duplicate sprites all over the screen ) which don't show on OpenMSX. Looks like there are some timing or initialization issues.

I did a quick test, the second monitor doesn't like 60hz/NTSC but still I can see the following (here the slow down function of the Sony 2+ finally is usefull ):

• Up until 'Loading SPR Earthquake' nothing is visible (only the VRAM gets cleared)
• At 'Loading SPR Haohmaru' the right sprite becomes visible
• At Enable layer B only the background becomes visible (so it looks like layer B is on top now, or the layers are swapped. I do see in your code that you put the sprite priority at 0 so would expect to be visible even in front of layer A)

After a reset of the MSX, before clearing VRAM again both sprites are visible so it looks these are loaded fine.

Anyway the emulators should behave accordingly. I hope it helps them to improve.

It looks like it has something to do with R#22, I observed before the following strange behavior:

This doc (http://msxbanzai.tni.nl/v9990/manual.html) says:

SDA	: Set to "1" to disable layer "A" and sprites.
SDB	: Set to "1" to disable layer "B" and sprites.

But on the emulators it doesn't disable the sprites, only the layer, so I trust this to disable only layer A.

To emulate hardware well known is hard, hardware most obscure is even harder.