byuu says:

I started working on the Toshiba TLCS900H CPU core today.

It's basically, "what if we took the Z80, added in 32-bit support, added
in SPARC register windows, added a ton of additional addressing modes,
added control registers, and added a bunch of additional instructions?"
-- or in other words, it's basically hell for me.

It took several hours just to wrap my head around the way the opcode
decoder needed to function, but I think I have a decent strategy for
implementing it now.

I should have all of the first-byte register/memory address decoding in
place, although I'm sure there's lots of bugs. I don't have anything in
the way of a disassembler yet.