Hiya Adrian!
(Waves...)
I'm Mick, that collector in Leyland. My current collection of Nascom & Gemini stuff (and quite a bit of info) is at
http://www.nascom.info
Funnily enough, I started reading this forum yesterday in the hope that there might be something on disk interfacing for the Gemini. I've been tidying out my shed and came across a "kit" (i.e. pile of bits) for what I assume was my old Nascom-1 19" rack. It made me think that perhaps it's time I had a working Gemini. I have previously tested a GM813 and an IVC and they appear to be working - unlike either of the Gemini keyboards that I have. I've just ordered one of the cheap logic analyzers off ebay so figuring out what's up should be easy enough with that.
Currently I've no means to read & write EPROMs so that may have to wait a while. I don't think I have anything that I haven't seen mentioned on here already though. Actually, the whole project is going to have to wait until I've finished sorting the shed out. lol.