Yea, it's a lot of fun. I did this with a 6502 over Christmas vacation years ago. Mind, it was a 6502 emulator, not a specific system. My goal was to get Fig Forth up and running on it. I wrote it in Java, and had my own console, as well as CPU level breakpoints and such for testing. It supported the simple "serial" console and simple block disk I/O.
So, not only did I write the emulator, I wrote an assembler to assemble the stock Fig source code.
It's hard to express how interesting it was testing unknown source code, with a buggy assembler, on a buggy CPU. For extra loads of laughs, my "benchmark" system that I happened to be testing opcodes and such against (for flags and what not) was a buggy web emulator. You just never knew what was going to go wrong where. Amazingly, I sussed it all out.
The good news is that the Fig source pretty much worked out of the box. Outside of my minor changes to adapt to my "I/O", it worked really well.
So, not only did I write the emulator, I wrote an assembler to assemble the stock Fig source code.
It's hard to express how interesting it was testing unknown source code, with a buggy assembler, on a buggy CPU. For extra loads of laughs, my "benchmark" system that I happened to be testing opcodes and such against (for flags and what not) was a buggy web emulator. You just never knew what was going to go wrong where. Amazingly, I sussed it all out.
The good news is that the Fig source pretty much worked out of the box. Outside of my minor changes to adapt to my "I/O", it worked really well.