Weird bug in my emulator! [SOLVED]

1. Running the Stars Demo (PD), I got an invalid opcode ($12), and the emulator tries to RESET.
2. Loading a new ROM makes the bug to trigger... see the screenshot. Not only that game, but any other.

WTF is that?

It is some assembly code error. An opcode is a number for the instruction that is running. What ROM are you playing? I'd recommend using Nestopia as your emulator.

http://nestopia.sourceforge.net/

You must be kidding...

1. The ROM ends up reading from un-cleared RAM starting at $0784. Emulators that initilize RAM with $FF will end up eventually at instruciton $12. If you initialize all RAM to 0 instead, the demo should run just fine.

2. Not sure aside from stating the obvious that something isn't being reset properly.

Yeah, that's a known problem. ^_^;;


Did you said... OBVIOUS?

Joke aside, it's not happening on soft/hard reset, or even when I load another ROM. Weird and found it by accident.

Added to list of bugs in widespread homebrew and hacks

Found the problem. The gfx frame pointer wasn't being set to zero. Well, it was an obscure problem... but I guess details won't be interesting anyways. ^_^;;

What's going on with Chu Chu Rocket?

Nothing. It was a bug in my emulator frame pointer.