Mystery: game Bestial Warrior with corrupted colors in MSX1

Maybe part of the puzzle: the VRAM access speed limits only apply during active display. Is the bitmap update done during blanking?

Yes, that a good clue, I'll check it. However, openMSX takes this into account I guess.

Even adding the extra cycles still it's far away from 29.

About the blanking, I have to check.
But to me the most weird is that it works well in MSX1 and not with openMSX. An actually if you look at the code, assuming that it's not during the blanking and the 9918 timings in openMSX are correct, indeed it's normal that the emulated version does't work.

That game was released in Spain, where there were way more MSX1 than MSX2. Thus, it's really strange that the authors released something that actually didn't work well in a MSX1. I mean, you realize quickly that something is wrong as soon as you run it. And I don't remember (but memories are tricky) that it wasn't OK when I played with it.

The best would be to test it in a real MSX1. That I don't have here, ouch!

but the add hl,de : outi goes in 30 cycles.

I remember screen corruptions back in the day in my brother's MSX, a SVI-738; but can't remember the same of my own machine, a HB-75S...and probably with "Bestial Warrior", it rings a bell. Having bad timed video routines makes the game prone to fault but I guess that it depends on the hardware itself and its tolerance.

Thanks jltursan and Manuel for the clues.

Araubi told me that Obliterator has also problems. So I debuged it too to figure out why.
And I found the following:
- It writes the bitmap with a delay of 27 cycles between outs: OK
- It writes the CT with a delay of 17 (!) cycles between outs: TOO FAST! (to the best of our knowledge)

Now, let's compare with Bestial Warrior:
- Bitmap: 30
- It writes the CT with a delay of 17 (!) cycles between outs: TOO FAST! (to the best of our knowledge)

In conclusion, both games write the bitmap using enough, but the color table with 17. To me, that's not a coincidence. It seems that you can indeed write the color table faster than what is explained in the documentation.
Both games show corruption in openMSX (as expected) with any MSX1 VDP.
But we don't recall seeing that corruption when running in real MSXs (unless our memories are also corrupted

I'm waiting for araubi to confirm than Obliterator shows correctly in a real MSX1. If that's the case, it would probably mean that the VDP slots in VDPAccessSlot.cc for MSX1 in openMSX are not accurate.