Software backup loader exploit thing for the Sony PlayStation 1.
For more information on Tonyhax specifically, look at its section at orca.pet.
This version has basic support added for the MemcardPro/SD2PSX Memory Card Devices to send GameID. It detects and supports a card in the first slot ONLY. No page change support or otherwise.
It may also be compatible with ps1digital, not sure if PicoMemCard supports GameID?
It utilises the MemCardPro_ASM library from Cybdyn.
https://github.com/Cybdyn-Systems/MemCardPro-ASM
Protocol outlined here