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PostPosted: Wed May 13, 2015 6:18 pm 
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The Action 52 games "Alfredo" and "Jigsaw" both crash because they have $7C (3 byte NOP) at $AE96. Emulating as a 3 byte NOP causes both to go into an infinite loop, and the games never load. Simply bypassing the opcode (and subsequent unofficial opcodes) allows the games to boot up ok.


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PostPosted: Wed May 13, 2015 7:32 pm 
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isosceles wrote:
The Action 52 games "Alfredo" and "Jigsaw" both crash because they have $7C (3 byte NOP) at $AE96. Emulating as a 3 byte NOP causes both to go into an infinite loop, and the games never load. Simply bypassing the opcode (and subsequent unofficial opcodes) allows the games to boot up ok.


I vaguely recall the AVGN reporting that a few of the Action 52 games failed to start on a real NES.


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PostPosted: Wed May 13, 2015 8:08 pm 
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I vaguely recall the AVGN reporting that a few of the Action 52 games suck.


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PostPosted: Thu May 14, 2015 12:22 pm 
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Espozo wrote:
I vaguely recall the AVGN reporting that a few of the Action 52 games suck.


I do not recall the AVGN reporting an Action 52 game that did not suck.


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PostPosted: Thu May 14, 2015 1:40 pm 
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That Action 52 thing is a bug, it's supposed to be $4C. See here for original post: viewtopic.php?f=2&t=8357&start=15


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PostPosted: Thu May 14, 2015 1:44 pm 
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isosceles wrote:
The Action 52 games "Alfredo" and "Jigsaw" both crash because they have $7C (3 byte NOP) at $AE96. Emulating as a 3 byte NOP causes both to go into an infinite loop, and the games never load. Simply bypassing the opcode (and subsequent unofficial opcodes) allows the games to boot up ok.


What does "bypassing" an opcode mean? Do you mean treating it as a 1-byte NOP instead?

Though, if we are making a suggestion about how to run these games correctly, I think an IPS patch would be a much better way to help than to recommend modifying an emulator around the game's bugs.


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PostPosted: Thu May 14, 2015 4:00 pm 
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rainwarrior wrote:

What does "bypassing" an opcode mean? Do you mean treating it as a 1-byte NOP instead?



Yes.


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PostPosted: Fri May 15, 2015 8:50 am 
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rainwarrior wrote:
Though, if we are making a suggestion about how to run these games correctly, I think an IPS patch would be a much better way to help than to recommend modifying an emulator around the game's bugs.
That is correct I agree, use an external patch. (Same things can also be done for working with improper headers)

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PostPosted: Sun Jun 21, 2015 5:46 pm 
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Ninja JaJaMaru-kun uses $04 (NOP). This happens when you touch an enemy.


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PostPosted: Mon Oct 12, 2015 12:15 pm 
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Chester Field uses implied NOP $1A at $C97A (when you jump).


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PostPosted: Thu Oct 15, 2015 8:07 pm 
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I noticed that Sachen's Dancing Blocks uses SLO abs ($0F) as a three-byte NOP. It looks like they're just there to confuse a disassembler—most of the instances are in the copy detection code.


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