I've been working on a NES emulator for the past week, and I'm at the point where it's running a bunch of stuff perfectly fine and failing spectacularly when it comes to other things, which unfortunately means that I have trouble telling exactly what is wrong right now.
As far as the first two issues go, I think they're related, but I'm not familiar enough with what opcodes FF1 uses to wait for scanlines when it displays the dialogue box. In FF1, the dialogue box comes short a few pixels, so I'm adding cycles somewhere where I shouldn't.
(As for Battle of Olympus, it'll keep flickering back and forth between those two when on a certain spot of the stairs, as well as when you talk to people in the game. Whenever you're just walking on flat ground or fighting stuff though, it works fine.)
The second issue is this:
The first column of the background above the player character sprites is misaligned for some reason, and while I'm pretty sure it isn't because of VRAM mirroring, I'm also not sure what might be.
My third issue is with Castlevania:
For some reason, it ends up loading the wrong sprite data after the title screen. Most stuff, but not all, is garbled. Is there something about the VRAM address register I've got wrong? (A lot of other mapper 2 games work perfectly fine, such as Contra, Megaman and G&G.)
FF2 also locks up right as the first battle is about to start, like this:
This might be related to one of the previous bugs, but I know I had it running a bit further (with the wrong graphics) and then crashing when selecting something from the menu. (Not sure what was changed between then and when it stopped working, sadly, FF2 wasn't the game I tested the most often.)
As far as the first two issues go, I think they're related, but I'm not familiar enough with what opcodes FF1 uses to wait for scanlines when it displays the dialogue box. In FF1, the dialogue box comes short a few pixels, so I'm adding cycles somewhere where I shouldn't.
(As for Battle of Olympus, it'll keep flickering back and forth between those two when on a certain spot of the stairs, as well as when you talk to people in the game. Whenever you're just walking on flat ground or fighting stuff though, it works fine.)
The second issue is this:
The first column of the background above the player character sprites is misaligned for some reason, and while I'm pretty sure it isn't because of VRAM mirroring, I'm also not sure what might be.
My third issue is with Castlevania:
For some reason, it ends up loading the wrong sprite data after the title screen. Most stuff, but not all, is garbled. Is there something about the VRAM address register I've got wrong? (A lot of other mapper 2 games work perfectly fine, such as Contra, Megaman and G&G.)
FF2 also locks up right as the first battle is about to start, like this:
This might be related to one of the previous bugs, but I know I had it running a bit further (with the wrong graphics) and then crashing when selecting something from the menu. (Not sure what was changed between then and when it stopped working, sadly, FF2 wasn't the game I tested the most often.)