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 Post subject: Castlevania IIIe issues
PostPosted: Tue Jan 25, 2005 3:57 pm 
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I'm having a bit of trouble getting CV3 working. Currently, I know of two problems:

1. The intro switches CHR pages too early. i.e. it switches to the character pages for the next screen before it's finished with the current one. I suspect this is IRQ related, but I'm not quite clear on when the IRQ triggers (it says based on scanline, but at what point in the scanline? And is it scanlines since the value is set?)

2. In the first level, the vertical scrolling portion is messed up. It scrolls by tile instead of by pixel. This one, I'm clueless about.

Anyone happen to know the answers to any of these questions, or where to look?


Thanks,


Josh


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PostPosted: Tue Jan 25, 2005 4:17 pm 
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Tell me if you're trying to emulate the japanese version OR the american version... :)

I bet the USA version. This mapper might be 'a pain in the neck' to get it working correctly. Personally, I gave up, even with preliminary support... :(

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 Post subject:
PostPosted: Tue Jan 25, 2005 4:22 pm 
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Ah, I typed "IIIe" in the title but not in the text...yeah, it's the MMC5 version, and I'm only currently interested in emulating the MMC5 as far as necessary to get Castlevania working. So no ExRam, etc. There's definitely SOMETHING wrong with my IRQ emulation, I've fixed part of that problem, but not all of it yet.


The vertical scrolling, though, I have no idea.


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PostPosted: Tue Jan 25, 2005 5:53 pm 
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Is there a value written to the MMC5 registers during the vertical scrolling parts that parallels what you think the fine scroll should be doing? It's possible that even without EXRAM, the MMC5 is interfering in something screen related.


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 Post subject:
PostPosted: Tue Jan 25, 2005 7:57 pm 
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Hey Drillian, long time no see ya. Hopefully this will help you as much as it has helped me:

http://tripoint.org/kevtris/mappers/incoming/mmc5.txt

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 Post subject:
PostPosted: Tue Jan 25, 2005 9:23 pm 
Hyde: Yeah, that's what happens when real life catches up to me. I have the tendency to disappear for long periods of time. And I finally solved the Battletoads problem (though I am not entirely sure what fixed it, it's fixed and that's what matters :D )

Thanks to all of you for the help! Got it working really damned close to the real thing :) Well, at least Castlevania. Every other MMC5 game is going to be broken as all hell. But right now, I don't give a shit.


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 Post subject:
PostPosted: Tue Jan 25, 2005 9:25 pm 
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Okay, for starters, never accidentally post as a guest. Because when you type something that you want to change "i.e. 'I don't give a shit,'" it's not changeable.

Secondly, yeah, that was me :)


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 Post subject:
PostPosted: Wed Jan 26, 2005 2:39 pm 
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Anonymous wrote:
And I finally solved the Battletoads problem (though I am not entirely sure what fixed it, it's fixed and that's what matters :D )


Turns out all you have to do is "add" a few cycles between the time you set the VBlank and execute an NMI. I believe you also have to update the V counters on cycle 252 (rather than on cycle 256) to get it working right.

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 Post subject:
PostPosted: Wed Jan 26, 2005 6:08 pm 
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...:|
You say before pixel 256, but I still can't understand (err... hi Anes!) about how to avoid the 1-pixel line distortion on screen... if my explaination makes any sense..? :P

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 Post subject:
PostPosted: Wed Jan 26, 2005 8:00 pm 
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Not quite sure what you mean, Fx3. Hyde's referring to my comment about Battletoads, where level 2 would lock up if the timing were off. He'd been helping me try to solve it back on the old boards.

Yeah, I did change the V counters to cycle 251 to get it working, I remember now (it's been a while). But if I change it to 252 right now, it'll lock up when I'm almost through the level (like, right at the end it locks). Oh well, 251 doesn't seem to be hurting anything (though I'm sure it is, somewhere).


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 Post subject:
PostPosted: Thu Jan 27, 2005 12:38 am 
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Fx3 wrote:
...:|
You say before pixel 256, but I still can't understand (err... hi Anes!) about how to avoid the 1-pixel line distortion on screen... if my explaination makes any sense..? :P


Dude, it's like macumba: you either believe that it works or that it does not... And no, I can't really understand what you are trying to say :D

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 Post subject:
PostPosted: Thu Jan 27, 2005 12:01 pm 
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I don't believe in 'macumba'... :P

When the scroll regs are refreshed, don't you do "ppu_refresh += 0x1000" (meaning the fine-Y scroll)? Is this is done before pixel 256, a 1-line distortion will appear. I might post a screenshot of what I mean.

Image Image

In fact, I render the screen by taking the scroll regs immediately.

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 Post subject:
PostPosted: Thu Jan 27, 2005 12:12 pm 
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I do the following in my emu:

- Increase X scroll every 4th cycle (4, 12, 20, 28, etc)
- Increase Y scroll on cycle 252
- Reset X scroll (LoopyV = (LoopyV & 0x7BE0) | (LoopyT & 0x041F); ) on cycle 256

That with the delay after the 2002.7 flag is raised before an NMI is triggered... and Battletoads runs wonderfully. No distortion in any games.. everything works great.


If you're having distortion troubles, Fx3, it might be because you're not doing the pixel pipeline properly? Remember that images are loaded 9-16 cycles before they're actually drawn to the screen. So changing scroll values on 252 changes the scroll -after- all the tiles have been loaded... the remaining pixels being drawn to the screen on the scanline are already in memory.


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 Post subject:
PostPosted: Thu Jan 27, 2005 1:46 pm 
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It's going off-topic... but anyways... :D

Okay, but one more thing... Does Rad Racer 2 work with no glitches at right of screen?

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 Post subject:
PostPosted: Thu Jan 27, 2005 1:48 pm 
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I see glitches in Rad Racer (1) when you go off to the left in my emulator, but nothing in RR2.

And there's no harm in this going off topic, I've solved my problems (thanks again for the help!) :)


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