Mauro Xavier Retro Developer
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Tough weekend developing the FFU
🕑 Added 2022-06-20 16:01:14 +0000 UTCIt took two full days to improve the code, solve very unexpected bugs and implement important features.
I optimized the code so much that some resources using DMA (Direct Memory Access) needed to be changed to use CPU, and others needed to use the DMA_QUEUE method, which inserts the data in a buffer that is processed at each vblank.
When we break the 4Mb barrier I recompiled SGDK enabling the bank switch, and the instabilities nightmares haunted me again and I felt some drops in performance.
For now, we disabled the bank switch flag in SGDK and keep it as was.
Well, Mortal Kombat Trilogy was a great achievement for the Mega Drive and uses 8Mb without a bank switch too, but if you play it in a cartridge format, it obliges you to disconnect SEGA CD and 32x if you have it, as it uses the same memory space that any expansion use.
MAYBE, just maybe, our Final Fight Ultimate go the same way as the MKT, using up to 8Mb without bank switching.
In short, all this delayed the upload of a full gameplay video of round 1, but I hope this week this can be done.
Feel free to ask anything!
Comments
Mauro Xavier
You right, it was my mistake. The correct is 4MB (32Mb) / 8MB (64Mb).
FM
Understood and thanks for the clarification. I suppose you were talking about Megabytes not -bits? Sorry, my bad - I read 'b' as 'bit' vs 'B' for 'byte'.
Mauro Xavier
The use of bank switching above 4Mb is a limitation of the console itself and is a method that needs attention and accurate timers. I will have to do more tests about it in the future, for now we will leave it off to develop in peace.
FM
I personally wouldn't mind either but I think it would be a pity ... is that an SGDK issue? If so, maybe there's somebody in the dev community who is able to provide the additionally required code? Anyways, I hope this doesn't slow down your work too much - I'm super excited to be able to play FFU myself sometime in the hopefully not too distant future. :-) ... but for now I'm simply looking forward to the next video.
Lucas M.
I see! Still, I think it's quite valid to remove bank switching to ensure that performance isn't affected. Thanks for the answer!
Mauro Xavier
Probably it will not work in consoles "all-in-one", but the decision to remove the bank switching it's not definitive, maybe this can be changed in the future.
Lucas M.
I think it's ok to remove Sega CD and 32x when playing FFU. However, a question remains: could it cause incompatibility in models that have the Sega CD already added to the Mega Drive hardware, such as the Sega CDX or Wondermega? Maybe it's very difficult for someone to have a Wondermega, but will it have problems for someone who will play on CDX?
