Sleep/Restore and Save States broken with Inside Gadgets MBC5 Rumble carts

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(brought to my notice by Churchdill)

Using the physical Inside Gadgets MBC5 + Rumble cart:

• On the title screen it seems able to restore the screen and a moment of audio from sleep, but then crashes (appears to execute random GB code).
• During gameplay it is not at all successful restoring from sleep and just seems to go blank
• Even just capturing a save state (analogue button + up) causes a game crashes, sometimes triggering rumble during the crash. The save state gets created, but when loaded the game crashes instantly.

Using a similar version of the ROM but targeted to 32K no save on a Catskull bare 32K cart with no save RAM:

• Able to sleep and restore (title screen and in gameplay)
• Able to save states and restore (title screen and in gameplay)

Using the same ROM in the GB core (no cart):

• Able to sleep and restore (title screen and in gameplay)
• Able to save states and restore (title screen and in gameplay)

More with the IG Rumble Cart:

• Running a different build of the same ROM targeted for MBC5 + SRAM + Battery (0x1b) with NO Rumble still has crash problems with Sleep and Save States

• Running a < 16K program on the same cart with the same config MBC5 + SRAM + Battery (0x1b), Sleep/Restore and SaveState/RestoreState both work no problem.

So perhaps there is some problem with tracking or restoring the currently active bank for the upper 16K ROM region on this cart.

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Alex of Inside gadgets noted:

Looks like an aP thing, you have to trick it so it won't try and do other things. I just set the MBC to none and it seems to work now for sleep/wake. Same thing happened with MBC3 carts, it just overwrites the rtc data so you set the header to be MBC5 and then it doesn't overwrite the rtc data

rumble_cart_test_roms.zip