OK, so I've been buying more retro computing from eBay again. This is the latest:

I remember that one of my school friends had one of these, it's only taken me a couple of decades to catch up. So I've set about writing my own transfer software to move data between the Z88 and the PC. So far I have a BBC Basic program that runs on the Z88 and a C# .Net application that runs on the PC. Binary files can be transferred, so I can back up my files (including program listings) off the Z88. Maybe I'll show you the cable I made, it's a serious DIY job.