@328gts
Unfortunately, MIDI is not implemented in the OS4 port
It's because the program uses RtMidi class, which we don't have. It's my plan to have a look at it, though.
@anyone interested
As for the 303 emulation, you can of course play with it without a MIDI keyboard. In the "303 Units" panel, you'll need to create some bass groove patterns for a specific bank or banks. Then you'll trigger the given groove by specifying the bank (A-D) and pattern (1-8) in a track's Effect Column, for example:
31A1 will trigger pattern 1 in bank A of the first 303 unit
32B3 will trigger pattern 3 in bank B of the second 303 unit
During playback, the individual parameters can be automated using commands, just have a look at the documentation.
There's
an example video (which I didn't make but you can download it from my blogsite) to give you an idea.