I'm loving this emulator, really. Especially the accuracy-mode.

I've been busy doing some misc. homebrew ROM stuff to learn how the SuperFX chip works by using bsnes. Something has left me curious though: "backup-RAM".

It's mapped from $78:0000-$79:FFFF accoring to this page from the SNES dev manual book 2. There's a backup RAM register assigned to it too (BRAMR), with the description:
"Data becomes 'protected' when the BRAM flag is reset (0) after saving to the Back-up RAM".

This register is mentioned in the bsnes source, but the backup-RAM area isn't. Whenever I write to the backup-RAM area it acts like a mirror of the SRAM area. This feature isn't emulated in any emulator, as far as I know.

Is this left unemulated in bsnes on purpose? Or is this feature barely documented, or did you forget to emulate this? Or am I simply misunderstanding the function of backup-RAM? Just wondering. Any clarification would be great.

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My blog. I could post stuff now and then

My Assembly for the SNES tutorial (it's actually finished now!)

Yes, you would have almost all of the 64K APURAM for sound effect samples alone. Thus you could have a much larger echo buffer.



Any time I enabled this emulation, various games broke. Some even turned on the write protection and then expected to be able to write to it. Made no sense to me. So no, that feature isn't emulated. Same thing goes for the SA-1 equivalent functionality. It's a shame too because it's a trivial one line of code.

Anyway, I don't recall the SuperFX bus layout entirely. I was under the impression there was only one RAM chip on SFX carts, though.

To be fair there's netplay and everything