So, a couple of possibilities are to implement a Mips CPU, or convert one of them to use a Risc-V CPU. As they use a kernel with multiple processes and memory protection, the atomic instructions and possibly the MMU are probably needed. It looks like LiteBSD uses an MMU, but RetroBSD has been designed not to need one.
I would have thought Vexriscv could be made to work with them. For LiteBSD, at least, the new linux version of Vexriscv may be needed. It would be a project that I might like to try sometime, but not right now.
Did you mean the BlackIce II or the BlackIce Mx? I suspect the flash memory of the Mx is needed for the code.
