MBC7's accelerometer

[ReNardier]

i find it weird that you call this a superset of MBCn's yet it doesn't have the MBC7's unique feature, the lack of MBC6's re-writable flash is comprehensible and the lack of MBC4 is even more(it had a cable to connect into a n64 controller port and was going to be on DT: Lords of Genomes and GB Printer Cartridge(an updated GB printer that could do color) which connected with Mario Artist: Communication Kit, this idea home console & handheld connection was later realized with the GC-GBA cable, and id recommend you to not look further into the matter of the MBC4 due to the specks apparently being into the gameboy emulator of the 3ds, this was seen on the LEAKED CODE(that's the reason why i told you to not look into it))
but the lack of accelerometer still baffles me, specially since i think the rumble+accelerometer combination has only been seen on WarioWare: Twisted! for the GBA, perhaps a TPP2 is in order?

[aaaaaa123456789]

At the time of writing the specification, I was only aware of MBC1, 2, 3 and 5. Is there any documentation on the devices you mention?

[ReNardier]

https://gbdev.io/pandocs/MBC6.html
https://gbdev.gg8.se/forums/viewtopic.php?id=544
https://gbdev.io/pandocs/MBC7.html
https://gbdev.gg8.se/forums/viewtopic.php?id=448
for MBC7 since it's fully supported, i suppose it won't hurt to take look at it implementation https://github.com/mgba-emu/mgba
id also recommend you make the accelerometer a 3-axis one instead of the 2-axis that was used for MBC7, as you can see in the doc there where memory addresses for the z-axis that where left unused
and i assume you recognize the trouble that can come from data gleamed out of a leak, therefore i won't be linking you what is known about MBC4, although i assume you won't have that hard of a time finding it

[ReNardier]

although is you ask straight up, just to satiate your curiosity i will link you to it(the MBC4 stuff)

[aaaaaa123456789]

From the documents you linked, I'd say that flash is pointless to specify because the specification already says that writes to $4000-$7FFF pass through — if the underlying chip is a flash chip, you can control it that way.
I wonder how much complexity an accelerometer would add. My gut tells me it's not worth adding to the spec, but do you know if there's any interest?

[ReNardier]

on the MBC6's flash i fully agree, hence why i said i comprehended why you didn't include it into the superset
and on the MBC7's accelerometer, i can't guess on the complexity, your gut... well if it tells you something it might be for reason, id say the decision to follow it is on you, and as for interest id say that game making for a retro console is certainly a niche hobby, but would guess that those in it won't necessarily recoil in disgust from having some creative tools at their disposal, but id say something, given https://mgba.io/2022/10/11/mgba-0.10.0/#quality-of-life
"The accelerometers and gyroscopes in game controllers like DualShock/DualSense or Switch Pro Controller can be directly used in supported games, such as Kirby: Tilt ‘n’ Tumble and WarioWare: Twisted"
https://www.reddit.com/r/emulation/comments/y1tlzh/mgba_0100_is_out/
"Yes! I have to try this on Steam Deck. I would love to see the internal gyroscope supported as well.
Thank you endrift." 128 likes
which endrift responded to that post "It'll work under Steam Input, but it's hard to configure. You have to edit the config.ini by hand to add a gyroAxisZ key, and I can't remember exactly what to set it to (probably either 2 or 3), as well as setting the gyroscope to map to the right analog stick."
https://www.reddit.com/r/SteamDeck/comments/y20pgh/mgba_0100_is_out_and_it_supports_motion_control/
https://streamable.com/bbk8n9 a video of warioware twisted! being played with a dualshock(i think, i don't own a ps5)
id say that the tools to work and play with the accelerometer being mildly easy to come by, the "darn, i want to fiddle with this feature but i lack the tools" will not be that much of an impedance both for developers and players, so all in all, add or not the accelerometer at your discretion, after all you are the one that's going to devote their time on it