So, after spending all my time looking at various BIOS and CP/M and monitor sources for the RC2014, I've come to the conclusion that any system software I write for the system will completely subsume the BIOS.
The biggest reason for this is that each of these different components all seem to use different build tools. All of them, pretty little snowflakes each and every one of them. And HBIOS is the worst -- the ONLY way to build that is on Windows. And I don't have a Windows machine.