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irixxxx / picodrive

Fast MegaDrive/MegaCD/32X emulator
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Sonic Megamix 2007 build doesn't crash upon pressing C button #142

Open freq-mod opened 1 month ago

freq-mod commented 1 month ago

Similiar to #141 - something does work when it shouldn't. Sonic 1 Megamix SHC2007 build has a prroblem when, upon hitting C button on gamepad (jump) the game "crashes" and doesnt restart the execution until is pressed once again. it happens all the time throughout the game. This happens on real hardware, both Model 1 PAL and Model 1 NTSC-J, on Everdrive v3.

Thais is how the behaviour looks like: https://youtu.be/CWZtVb5FG2Q?si=jBCJy5tUnKlchtSN&t=458

On PicoDrive, the game runs perfectly fine, no crashes at all, which isn't an accurate to real hw behaviour.

irixxxx commented 1 month ago

This is the culprit: 17062: 4a78 fe19 tstw 0xfffffe19 causes a 68k address error.

PicoDrive has address error detection turned off for speed reasons. I have never observed this in any commercial title, so it's probably save to just ignore it.

freq-mod commented 1 month ago

Well, if performance hit wouldn't be too big even on 32-bit MIPS/ARM, it would be great to implement it, if one were to use PicoDrive for testing homebrew/ROM hacks. Else, it can be forgone I guess