Hey all, I just wanted to post a few words to say that I haven't given up work on this!
Thanks to Chris Pile, who has patiently talked me through all my z80 and Sam woes, I've finally got a clue and may even have the silent version of wubtris up on World of Sam this weekend. I'm down to just a couple of bugs and then I want to give the front end a bit of spit and polish :) more soon...