Interesting, I hope that the archives end up available to the public. It'd be really neat to build some kind of functional emulator like the visual 6502 to play around in. Do it on a block level for the CPU so you can examine the state as things happen.
Funny you should mention that, because the Living Computer Museum wrote a high-quality emulator (ContrAlto) for the Alto. It's super-accurate, even emulating the microcode and hardware, and runs at the speed of the live machine. It includes a debugging mode that lets you examine machine state and step through machine instructions and microcode. Source: https://github.com/livingcomputermuseum/ContrAlto
Awesome I'll check that out. I think I remember looking back when this started and found SALTO but it appears to be incomplete and buggy. ContrAlto looks interesting.