Ran quick tests with beta firmware on my 1.x card.
Usb mode now works, at least cd mode.
Sb mode also works, tested quickly with world of xeen.
Gus mode works, tested with epic pinball.
As always xcom: ufo defence and panzer general does not work in gus mode.

One more beta release, if this goes well I'll release it as v4.1.1 final. https://github.com/polpo/picogus/releases/tag/v4.1.1-beta.1

In this one: fixes bad clicking in single-cycle DMA audio in SB mode (more than the typical clicking that non-autoinit SB titles can have).