Friday, 22nd February 2008
World Class Leaderboard Golf
Well, I've just about got it the way it was before with the new interrupt code; most games work again, but the few that have always given problems (such as Desert Speedtrap) still don't work properly. I think this is the stage where I have to start trawling through disassemblies to try and work out why they're not working.
Cosmic Spacehead - one of the few games to use the 256×224 mode.
One problem I still haven't got to the bottom of is with the Dizzy games. They either reset when starting a new game or lock up. I'm hoping this is a problem with my implementation of the Codemasters mapper. I guess that The Excellent Dizzy Collection has a simple front-end game selection screen that switches to the requisite ROM page for the selected game, then jumps to the start of that page - in my case this jumps back to the initial Codemasters screen.
I'm not sure where Fantastic Dizzy's problems originate. It looks like an interrupt problem (maybe the palette should be switched when the VDP has finished with the status bar at the top?), but could also be related to the other Codemasters problems.