PBP offers pretty limited support for the 12-bit core.

Calls and computed jumps can only be made to the first half (256 words) of any code page on the 12-bit core with PBP due to the meager resources on the 12-bit core.

And, all PBP library routines have to squeeze into the 1st page, so it's tough to do much with PBP on a 12-bit core unless you're pretty creative.