Out of the blue the other day, my friend found an internal 65C102 co-processor for the BBC Master in his attic, and gave it to me. It wasn't in particularly good physical condition (all the pins were bent) but I managed to get it connected, and it does appear to work! (Though I don't have any of the PCB stand-offs; I guess they're quite important to ensure the board isn't damaged by warping, so I should probably go and find some soon-ish).
However, I'm slightly more concerned than with most hardware, due to the condition that it was in, that there might be something wrong with it. While I can write a simple BASIC loop and see that it does indeed execute just over twice as fast as on the main processor, I'd like to test as much as the memory as is possible. I gather from the internet that the entire 64K address space of the thing is mapped to RAM, into which the chosen ROM is copied on boot? So I guess testing that bit won't be easy. Though I could easily write some BASIC to do some simple tests between PAGE and HIMEM (though that might be complicated since I suspect HIMEM especially will change during program execution!), and between &C000 and &F7FF (where "HI BASIC", which I also don't have a copy of, would usually sit), I wonder if there's a not-too-hard way to be a bit more thorough than this?
Unfortunately I've forgotten most things I used to know about my collection of 80s and early 90s home computers, since I had university between now and the last time I had access to them; so some basic things that I would have known how to do (eg getting files onto disk easily) are things that I can't do right now (especially since my main machine with a floppy controller is currently sitting dead). But I can remember the, err, basics of BASIC, and I can get files across using the tape interface.