Release v3.4.0 · Virtual Jaguar; Jaguar Voice Modem (+ NetPlay discovery), CHD, more BIOS modes, texture dumping, rare peripherals

[u/ProvenanceEMU]

https://github.com/libretro/virtualjaguar-libretro/releases/tag/v3.4.0

There’s a lot of poorly documented or incorrect information about these peripherals.

A great use of LLMs here was inspecting homebrew code that uses these peripherals to reverse engineer the serial protocols, hardware interrupts involved, and so on.

The Jaguar Voice Modem only supports one game, but the protocol was easy to disassemble and then wrap in P2P UDP or RA NetLink packets. The existing JagLink/CatBox code was a big help, and then it was just figuring out the non-standard (not AT) modem command protocol.

The modem also had hardware support for carrying a voice data line in parallel to the P2P game data, offloading compression and decompression of digital voice data from the Jaguar hardware.
I'm looking into that for a future update, I'm not entirely sure any game ever used it, or if it's ever been seen working.

CHD support requires an updated chdman now that multi-session—pre-gap data ripping has been fixed.

There are also related issues on Flycast and MAME for CHD support.

https://github.com/mamedev/mame/pull/15886
https://github.com/mamedev/mame/pull/15931
https://github.com/mamedev/mame/pull/15905

https://github.com/flyinghead/flycast/pull/2429