OK, thanks for the update.
I only got interested in the Archimedes because I was itching to do a CPU in an FPGA, and thought that an ARM2 would be a good choice. I've been collecting ARM and Archimedes doco, including the "datasheets" for the 4 main chips in the thing. I've started on the ARM2 (FPGA) but aside from a quick perusal of the doco I've downloaded thus far, I don't know a lot about this platform.
It's also been a _long_ time since I wrote a MAME/MESS driver - a private driver for some custom hardware for v0.79!
No doubt there's been plenty of changes since then!
Oh well, this is the _fun_ part - right! :P