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Zepper
PostPosted: Tue Jan 31, 2017 5:30 pm 
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In my emulator, the title screen has a green-ish color instead of black, and the game hangs after pressing START because of a RAM clearing routine, but always calling the JMP address from RAM $07F4.
Code:
6C, F9F7 JMP ($07F4)
48, CA01 PHA
A9, CA02 LDA #$00
8D, CA04 STA $E002
8D, CA07 STA $E003
68, CA0A PLA
40, CA0B RTI
D0, E962 BNE $E94D [A:0 X:F4 Y:10 S:F9 P:A0]
95, E94D STA $00, X [X=F4, Addr+X=F4]
9D, E94F STA $0200, X [X=F4, Addr+X=2F4]
9D, E952 STA $0300, X [X=F4, Addr+X=3F4]
9D, E955 STA $0400, X [X=F4, Addr+X=4F4]
9D, E958 STA $0500, X [X=F4, Addr+X=5F4]
9D, E95B STA $0600, X [X=F4, Addr+X=6F4]
9D, E95E STA $0700, X [X=F4, Addr+X=7F4]
E8, E961 INX
D0, E962 BNE $E94D [A:0 X:F5 Y:10 S:F9 P:A0]
95, E94D STA $00, X [X=F5, Addr+X=F5]
9D, E94F STA $0200, X [X=F5, Addr+X=2F5]
9D, E952 STA $0300, X [X=F5, Addr+X=3F5]
9D, E955 STA $0400, X [X=F5, Addr+X=4F5]
9D, E958 STA $0500, X [X=F5, Addr+X=5F5]
9D, E95B STA $0600, X [X=F5, Addr+X=6F5]
9D, E95E STA $0700, X [X=F5, Addr+X=7F5]
E8, E961 INX
6C, F9F7 JMP ($07F4)
00, 0000 BRK

Any clues? A CPU bug?
(after 2 milions and half lines of debugging code)


Last edited by Zepper on Wed Feb 01, 2017 1:58 pm, edited 1 time in total.

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James
PostPosted: Tue Jan 31, 2017 6:37 pm 
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It was hanging in my emulator as well, but I was able to get it to work by forcing the "old" IRQ behavior.

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Zepper
PostPosted: Tue Jan 31, 2017 7:13 pm 
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James wrote:
It was hanging in my emulator as well, but I was able to get it to work by forcing the "old" IRQ behavior.

It worked! Such option is already available in my emulator though.
One more question - what about the green-ish title screen?


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zeroone
PostPosted: Tue Jan 31, 2017 7:34 pm 
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The game works fine in Nintendulator. Nintendulator does not require old IRQ behavior to be explicitly set and it does not appear to detect the ROM in a cart DB. Maybe the issue is a bit more complicated.
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James
PostPosted: Tue Jan 31, 2017 8:05 pm 
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Took a quick glance at Nintendulator's source code, and it appears to be using the old IRQ behavior.

Zepper -- the green title screen is emphasis bits related. If I disable emphasis bit support, I get the same result.

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tepples
PostPosted: Tue Jan 31, 2017 8:45 pm 
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If a game is made for PAL famiclones, such as Dendy, it'll have the sense of green and red emphasis bits inverted. What does it look like with emphasis off, and what is $2001 set to?
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zeroone
PostPosted: Tue Jan 31, 2017 9:42 pm 
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James wrote:
Took a quick glance at Nintendulator's source code, and it appears to be using the old IRQ behavior.


That's interesting. I have it the opposite in my emulator (i.e. use the new IRQ behavior except in MMC3 variants that require it). I never noticed any issues until this game. Are there others I should know about?
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lidnariq
PostPosted: Tue Jan 31, 2017 10:40 pm 
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If Nintendulator is using the old behavior, then Star Trek - 25th Anniversary is supposed to not work correctly...
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zeroone
PostPosted: Wed Feb 01, 2017 7:52 am 
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lidnariq wrote:
If Nintendulator is using the old behavior, then Star Trek - 25th Anniversary is supposed to not work correctly...


I noticed that the Nestopia cart DB does mark some mapper 4 games as MMC3A:

Code:
<chip type="MMC3A" />


In my GoodNES audit, I treated mapper 1 games marked with MMC1A as mapper 155 games. Why isn't there a separate mapper for MMC3A games?
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Zepper
PostPosted: Wed Feb 01, 2017 9:40 am 
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tepples wrote:
If a game is made for PAL famiclones, such as Dendy, it'll have the sense of green and red emphasis bits inverted. What does it look like with emphasis off, and what is $2001 set to?

I tested it here. The green-ish background is still there. The emphasis bits are NOT inverted in this game, since the "Aladdin" word becomes green-emphasized if I swap the bits.
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thefox
PostPosted: Wed Feb 01, 2017 10:21 am 
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lidnariq wrote:
If Nintendulator is using the old behavior, then Star Trek - 25th Anniversary is supposed to not work correctly...

Yet it does.

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zeroone
PostPosted: Wed Feb 01, 2017 10:38 am 
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thefox wrote:
lidnariq wrote:
If Nintendulator is using the old behavior, then Star Trek - 25th Anniversary is supposed to not work correctly...

Yet it does.


What part of the game supposedly fails to work?
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tepples
PostPosted: Wed Feb 01, 2017 12:45 pm 
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zeroone wrote:
In my GoodNES audit, I treated mapper 1 games marked with MMC1A as mapper 155 games. Why isn't there a separate mapper for MMC3A games?

Because no licensed games are known to rely on MMC3A behavior (as opposed to MMC3BS/MMC3C). If this game does, then a proposal for an MMC3 submapper may be in order.
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Zepper
PostPosted: Wed Feb 01, 2017 1:10 pm 
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Any clues about the green as background color?


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zeroone
PostPosted: Wed Feb 01, 2017 1:54 pm 
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Zepper wrote:
Any clues about the green as background color?


How is that image different from other emulators? Even the mapper 114 (MMC3a variant) version looks like that.
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