Well, Andy, that's actually wrong, Kanata posted a picture on Twitter where we can clearly see the graphical glitch on screen and he's on N64 (https://twitter.com/kanata2s/status/724783344601292800?lang=fr) so for now we just have no idea how he got it, and testing on emu is so annoying the result is always random (sometimes I just get absolutely nothing... So for now I'll try to do that on my N64 PAL but it will take time and I'll also ask some other people who have a N64
I also took one more look at Cosmic Ark stars, but all I could come up with is that they are displayed differently based on different TIA revisions. I don't think this can be further resolved without analyzing the circuits, so I'm just going to set this aside and focus on known issues.
This is great. Finally, this run has an up-to-date Turbo Tunnel skip in level 3. There are some amazing changes elsewhere too. Of course, this raises the question of how many runs Battletoads should have. The any% and the 2-player warpless, I think, are pretty agreed-upon categories. Is this run valuable enough to be published separately from those other two? (This may just be a case of a legacy category that was more historically interesting, like the Princess SMB2 run.) One strategy question: why don't you recover your walker stick to fight Big Blag in stage 5? Each time you headbutt him, he pauses the game with his landing. If you took one of his small jumps as time to get the stick back, you can juggle him with the stick and keep him from landing.
With the implementation of PRG write delays, many graphical bugs are now fixed (such as the 'O' in power in H.E.R.O. above. )
This fix also correctly implements PRG delays due to HMOVE, which is what the hacked in original 3-2-1 code was trying to do.
This also fixes the rather annoying house moving bug in River Raid.
At this point pretty much all graphical bugs should be fixed.
So I have finally fixed the original bug that got me interested in all of this. This implements the same play field delays that Stella uses. While I don't understand why they would be true at a low level, they none the less have high compatibility and I haven't seen any deficiencies in my testing.
Wow congrats! For Stella, I'm not sure why. Given how it was mentioned that it uses a high level approach rather than a lower one, it (may be) the case that the devs simply made a random starfield effect and assumed it looked "close enough". Could be wrong however.
I mentioned above that HMOVE sends extra clock pulses down the same clock lines that are usually used during the visible part of the scanline. In theory this means that performing a HMOVE during the visible part of the scanline should have no effect. However, looking at how the various clock signals interact, I suspect it is possible. I did some preliminary experiments (on a 2600 Jr) at some point, and I seem to remember having some success.