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PostPosted: Wed Jun 02, 2010 5:39 pm 
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That's right. Okay, so that tells me that I should have the interrupt output of the mapper enabled upon reset. And even though the IRQ line will be asserted from the MMC3, the CPU is not going to recognize it until the user calls the CLI instruction. Makes sense. Thanks!


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PostPosted: Wed Jun 02, 2010 7:03 pm 
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Okay, so that fixed it. I am now passing _all_ of Blargg's MMC3 IRQ test ROMs. But unfortunately, when I say all I really mean _all_ of them - including _both_ Rev A and Rev B tests (#5 and #6). I don't think that's supposed to happen - in fact, I didn't even think it was possible. Well...more debugging. If anyone has any ideas let me know.

But hey, I'm passing all of Blargg's tests! Progress!! :)

Pz!

Jonathon


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PostPosted: Wed Jun 02, 2010 8:28 pm 
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Well this stinks. Now that I have _enabled_ the IRQ output by default Super Mario Bros 2, which used to work, is no longer working. And I can see that the game keeps jumping to FFFE-FFFF over and over again. I don't get. I didn't think that SMB2 even used the MMC3 interrupt at all. But apparently it does, otherwise why would they clear the interrupt flag (i.e. CLI)?

So if I make my MMC3 disable interrupts at system reset then I won't pass Blargg's tests but SMB2 will work.

If I make my MMC3 enable interrupts at system reset then Blargg's tests pass, but SMB2 no longer works.

Wha??

Any help?

Thanks!

Jonathon


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PostPosted: Thu Jun 03, 2010 5:12 am 
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jwdonal wrote:
I didn't think that SMB2 even used the MMC3 interrupt at all. But apparently it does, otherwise why would they clear the interrupt flag (i.e. CLI)?

I forget: Does SMB2 use DMC IRQ?


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PostPosted: Thu Jun 03, 2010 5:39 am 
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Don't recall if it uses DMC interrupts, but it definitely does not use MMC3 interrupts.

jwdonal - are you triggering interrupts only if they're enabled (i.e. by writes to $e001)?

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PostPosted: Thu Jun 03, 2010 8:31 am 
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There's no way SMB2 uses DMC interrupts, and I'm very doubtful it uses MMC3 interrupts.

(at least I doubt it uses MMC3 interrupts during the main game. It might use them for some subscreen or something)


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PostPosted: Thu Jun 03, 2010 8:33 am 
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SMB2 was originally MMC1 with CHR-RAM before it became MMC3 with CHR-ROM.

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PostPosted: Thu Jun 03, 2010 12:22 pm 
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Dwedit wrote:
SMB2 was originally MMC1


Interesting -- what's the story there? Was this just in development or something? I'm unaware of any non-MMC3 version of SMB2.

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PostPosted: Thu Jun 03, 2010 12:28 pm 
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James wrote:
Dwedit wrote:
SMB2 was originally MMC1

Interesting -- what's the story there? Was this just in development or something? I'm unaware of any non-MMC3 version of SMB2.

Dwedit is trying to say that early prototypes of SMB2 were SNROM, just like the other popular FDS ports (Metroid, Kid Icarus, The Legend of Zelda). It was mapper hacked to MMC3 before release, with new features such as animated background tiles and an expanded ending.


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PostPosted: Thu Jun 03, 2010 5:18 pm 
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cool page -- thanks.

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