Nothing all that exciting. A UK company called 'solidisk' made a RAM expansion for the BBC micro that took a bit of fiddling to install but worked quite well.
I used it for very limited black-and-white 3D animations, pre-compute the edges, then draw the images in real time and for other tricks.
A few months ago when trying to interface a bunch of hardware to a PC I realized how much easier such tasks were in the past, it's funny how we have made it much harder to expand a computer in our own domains (electronics, interface boards, standard ports with immediately usable i/o almost without latency) compared to how much easier it is to expand a computer towards the domains of others (networking).
I used it quite a lot when I got a bit older - the RAM disc's speed made it very useful. Good to play disc Elite (once unprotected...) from, and I remember it being much quicker to assemble stuff with ADE.
(I still have it, but the Opus EPROM erased itself long ago, so the RAM disc part has languished unused for a very long time. The 32 year old disc drive still works fine with my Master 128 though...)
Wow, I've seen a lot of BBC hardware (I had good contact with both Dutch importers of BBC related stuff) and I've never seen one of those.
You probably could re-program that EPROM if you wanted, or replace it with a ROM so you won't have that problem ever again. But this is probably not the most practical system for today :)
The comment about practicality is well made. The Challenger was a good device for the time, but for the modern day I prefer my current setup: Master 128 with 16MHz copro, plus home-made mashup of http://zeridajh.org/software/65link/index.htm and Minimus AVR, letting me can use my Macbook Pro as a file server ;)
Unfortunately I lost almost everything I ever wrote for 8 bit platforms and a lot of my early PC and Atari stuff. It's a real pity, but then again, it also forced me to cut ties with the past and move on which in a way was a blessing.
But it would have been nice to open up a lifetime of code at some point.
