i was super bored so i made a thing in my head. observe the photo.

and if i ever have the time in the future, i may or may not be interested in working on a project like this

open source ps2 modchip running on an rp2530. upgradeable.

don't hot-patch the bios. only tap the mechacon. the bios would be re-flashed entirely, instead. i don't know yet if flashing it from software on the ps2 would be possible, but you could always just re-solder a modified version.

@PCSX2 what do you think of this?

@libreleah hey!

Patching the BIOS in a non volatile manner is AFAIK not possible, esp since some revisions use non rewritable mask roms.
Also virtually all ps2 games already hot patch the bios to fix bugs, so your "don't hot patch" might be dead in the water to begin with (and also why a fully open source bios means it needs to be 1:1 with the original binary).

For the mechacon: you'd probably need to reimplement the FW, MITM with a failed region read would lead it to lock if it's ur usecase

@PCSX2 Yeah, I thought that might be wishful thinking. I was also aware that some boards use mask ROMs. My thinking was that if flash is used, then maybe their is a WP pin you could flip to enable writes.

Re-soldering a compatible, flashable flash IC would at least be feasible.

There is PCSX Redux Open BIOS for PS1, and it works nicely - and I know PS1 games patch the BIOS.

Probably not gonna work on it, but an open source modchip at least (hotpatching BIOS too) with RP2530 MCU would be cool.

@PCSX2 i also wonder, because the dev units didn't have copy/region protection, so you could use burned discs. i wonder if there's some secret hidden command you could send the mechacon to turn off all protections. that plus a modified bios might be nice (no mochip at all). not sure if possible, but for instance i know you can send a command to mechacon on the ps1, to disable the wobble check

those matrix infinity clones won't be around forever, so i was thinking something like psnee, for ps2

@libreleah Not that we know of. The mechacon firmware has been dumped thanks to mechapwn/mechadump and should be readily available. The overall authentication dance, crypto drm (magicgate) etc was reversed since a bit and I documented the general idea at fosdem a while back.

@PCSX2 That's amazing. Is there some documentation about that somewhere? I'd love to read it!

My ultimate aim is a free BIOS on PS2. I maintain a project, Libreboot, ostensibly a coreboot distro but it allows other firmware too. See:

https://libreboot.org/docs/install/playstation.html

This uses PCSX-Redux Open BIOS, and replicating something comparable for PS2 is something that I'd like to see done at some point - hence my interest in a more hackable modchip/BIOS setup, for debugging and such.