/vr/ - Retro Games

Illegal exception. You're using a cycle accurate emulator to play a rom hack.

By panning down while Sonic is offscreen, you're somewhat causing value $FFFFF6F8 (which is supposed start other subroutines to fill in the game's tiles) to wake up before the tiles supposed to display are actually decompressed.

This causes the game to read $FFFFF6E0 which is a pointer that feeds routines with some place to output the decompressed tiles. Since this pointer is supposed to initialize when the tiles are actually ready, it just rests to $00 any other time because it is not required.

What happens is that since $FFFFF6E0 is set to $00 you start decompressing data at $00000000, and since there is no jump at $00000000 the game tries to execute invalid code and crashes.

>>2691295
This is a logical exception, every sane emulator should be able to trigger it, it does not have anything to do with romhacks or accuracy. If anything, romhacks will have fixed this bug by making sure $FFFFF6F8 (or its equivalent) is not changed before having thoroughly decompressed the tiles. Sonic 3 did exactly this to fix the bug, which was left as is in 2.

>>2691291
Mexicans have crossed the border through your Sega Genesis and it's being shut down to stop the flow of illegals.

>>2691620
thank you based Trump

>>2691584
thank you

>>2691584
Great informative explanation, thank you.

>>2691291
You've been caught emulating. The internet police will be at your house momentarily.

>>2691291
I used to be able to get something like this to happen reliably in sonic when I was a kid, It was in star light zone but at the top of the screen.

>>2691620
So what you're saying is that we need to build the wall out of Sega hardware.

>>2691584
Posters like you are the reason I come to this board.

>>2691584

>>2693089
>>2693097
>>2696321
>>2696358
Actually, upon further reading, turns out $FFFFF6E0 normally points to the code for decompressing tiles, not where to output them. This makes even further sense. Still, the rest of my post was mostly correct. S-Sorry for the inconvenience.

>>2691584

>>2691620
Thanks Trump.
>>2691584
Thanks Jeb/Hillary

>>2696484

Where's Bernie to fix the error for free?

Did they ever fix this issue?