I'm a bit disappointed. It's not much like a 68000 at all, even if the assembler mnemonics are similar.
I was interested in the instruction encoding, because that's a very important detail for judging how much hardware would be needed to turn it into a real CPU, not to mention the code density. Oh yeah, and the novelty factor as well. 68K is pretty clever with how it encodes instructions and has very dense code. Among the "complex" CISC designs, 68K is pretty interesting.
The encoding of MC64K is actually a lot like x86 (!), as it just tacks on numerous extra extension bytes as modifiers, which is lazy. Like x86, you need to parse almost the whole instruction to determine how long it is, which is just silly. You can't easily add new instructions in the future without really going down the x86 route by adding opcode pages, which is messy. If you're doing to support variable instruction length, this implementation is a terrible way to do it, regardless of whether it's done in software or hardware.
