SpritesMind.Net

Actually, these bugs happen in every emulators, but I left this here for easier bug references

This will happen after "Two Faces" drops bombs on you:

1) partial corrupted line on the top-right part of the screen: what happens is the game uses 2-cell VSCROLL mode and is modifying VSRAM data for that line during the previous line, which shifts into the HBLANK period for the two or three last values. Most emulators will either render the line or latch VSRAM before those last values got written and the two or three last 16-pixels columns are incorrectly rendered.

--> it means that VSRAM values are not latched in 2-cell VSCROLL mode and most likely read by the VDP before rendering each 16-pixels column. Analyzing game timings shows that it writes VSRAM values on the previous line AFTER the associated 16-pixel column has been rendered, so it will only takes effect on next line. From emulator point of view, it is only necessary to make sure that, in this mode, VSRAM writes during HBLANK are still taken in account for the upcoming line.


2) full corrupted line in the middle of the screen: what happens is the game is writing VDP register #4 during HBLANK to modify Plane B nametable address from that line. Most emulators will render this line at once before this address is changed and got it wrong.

--> it means that planes nametable registers are not latched at the start of the line and can probably be modified anytime during a line. As I see it, VDP regs #2 #3 and #4 are read by VDP before reading each pixel data block from VRAM. Again, from an emulator point of view, it is only necessary to make sure that, nametable changes during HBLANK are still taken in account for the upcoming line. I didn't verify if this is only the case in 2-cell VSCROLL mode but most likely not.


Funny that we are still finding games doing odd tricks like that, after all these years

Very nice finds
Batman & Robin is one of the most impressive genesis title when it comes to GFX and rasters effects. I'm not surprised to see that emulators doesn't reproduce it 100% accurately.

I agree, the developers did an awesome job and each boss/stage has some original gfx effects...

But it's also damn hard, I had to use game genie codes to simply go to that part

Eke wrote:I agree, the developers did an awesome job and each boss/stage has some original gfx effects...

But it's also damn hard, I had to use game genie codes to simply go to that part

Yeah the game is very difficult, i used a cheat code too to see next levels (you don't need game genie, some cheats exist to choose / change level ingame).

Honestly the game isn't that good... Which is too bad because I love this Batman cartoon, and as noted it's pretty as hell.

We were talking from a technical point of view, and from this point, the game is just awesome. Also it has some very impressive sound tracks, one of the best on the sega genesis imo.
Beside that, the game is very difficult, and somewhat frustrating to play with...

I agree, this game often rise a "FFFFFUUUUU....." exception in my brain.

I must be one of the few people who actually enjoys this game.

I do like this game, but again, somewhat frustrating as it's very difficult (at least for me).

Thanks for the bug report . Will be fixed whenever I get the time.

Btw, yeah the game is hard. I used to use cheats on this game as well.