It is currently Tue Apr 24, 2018 10:17 pm

All times are UTC - 7 hours





Post new topic Reply to topic  [ 2 posts ] 
Author Message
PostPosted: Tue Apr 24, 2018 6:01 pm 
Offline
Formerly Fx3
User avatar

Joined: Fri Nov 12, 2004 4:59 pm
Posts: 3098
Location: Brazil
I added Acclaim's IRQ timing, of IRQ counter clocking on falling edges of A12. This way, Mickey games work much better. From my attempts of getting this game working fine, I'd like some advice on it. Ages ago, someone said that the only difference is about Acclaim's IRQ triggered 4 cycles later if compared to MMC3. That's NOT the only difference from my attempts.

Is Numberland the same board/IRQ system of Letterland? Numberland expects the IRQ counter to be always clocked, even after a IRQ counter reset (so, the new value would be irq_latch-1), but Letterland expects the "normal" behavior - of checking irq_counter == 0; else, decrement it. Well, if I apply the Numberland behaviour, Letterland has a scorebar of 1 scanline shorter in size.

If I ignore $2006 writes, there's no scorebar shaking.
If I fix Letterland, Numberland is glitched by 1 scanline (IRQ timing is off by 1).
If I fix Numberland, Letterland is the glitched one, but I believe it's what a NES console does.


Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 9:58 pm 
Offline

Joined: Thu May 19, 2005 11:30 am
Posts: 505
Mickey's Safari in Letterland uses Acclaim's MC-ACC chip (mapper 4 submapper 3), Mickey's Adventures in Numberland uses a regular MMC3C chip (mapper 4 submapper 0). Implement MC-ACC by raising IRQ four PPU cycles after PA12 goes high (versus 0 on MMC3) and by ignoring further PA12 rises for 35 PPU cycles (versus 8 on MMC3). Mickey's Safari in Letterland's scorebar seems to depend on the latter aspect.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group