So, now I have a keyboard, I decided to do something to make use of it. BASIC seems appropriate, so I "ported" EhBASIC to my system, including TMS9918, character LCD and 128x64 graphics LCD drivers.
In doing so, I discovered a bug in my emulator. The BIT opcode in the 6502 library I was using didn't set the processor flags correctly. So, I tracked that down and fixed it.
All the code is available and you can follow along using my HBC-56 emulator (also in the GitHub repo).
If you've been thinking about BASIC for your 6502 build, it's not too hard to do.