Petition to fix sprites on Valis on MSX2.

if there is time one can try.

most games have this kind of code to write VRAM

outi
outi
outi
outi

it is necessary to replace this routine with a little more complicated where the out of the third byte is replaced with 0. then a similar loop should be used to fill vram. for each sprite.
If there is time.....

Thanks, I know, it was a play on that.

Well there are some degrees. Appart from the sprites they are pretty much the same.

As Pingpong suggested it isn't too hard to replace SAT updates to be screen4 compatible. Maybe it gives slowdown due to the extra colordata you need to write.

But adding sprite rotation (or an other flickerng routine)and upgrading the sprites (more colors) takes some dedication.
Adding smooth scroll is pretty much like rewriting the game engine as all movements are 8 pixels.

Yes,but is does not take extra cpu time. That's because every game i'm aware of, does always a full blit of the entire sat at every frame, despite the game uses or not sprite rotation.
Plus, a more primitive form of sprite rotation (that is the same used in most games) can be done by replicating the SAT 4 times. Every frame you write to a different SAT address, and every SAT have pre-rotated sprite color attributes by 8 sprites entry, so the z80 only write the 128bytes part of the SAT, because colors are fixed and already prerotated. However this can only work if you do not change to often sprites colors. In some games this can be done, because enemies are linked to sprite priority planes so their colors are also fixed or they change rarely