How does VD0 relate to the RAD disk that came with AmigaOS eventually?
VD0 might be a great-grandfather of RAD. Probably grandfather. The German kid's version would be Son-Of-VD0.
Oh, I remember now. My disk didn't resize dynamically - it ALLOCATED dynamically. At least some of the other recoverable ram disks that came later allocated all of their space in one go. I think there was one that finally allocated dynamically and resized dynamically but that wasn't mine. Actually, to be honest, I don't remember for sure if mine allocated dynamically or not, I know I did
something that was better than the next RRD that came out. I have backup tapes that have the source code for everything ASDG did but no way to read them (assuming they are still readable).
Apart from this distinction there was little functional difference between them. In practical terms, however, the newer RRDs were faster and smaller. The smaller wasn't by much - we're only talking a few kilobytes at most.
I think the main things that make VD0 important are:
a) How early it was in the commercial life of the Amiga - it was 1985 or 1986.
b) How big a problem it remedied - I know for sure that several major software products would have been much more difficult to write had the authors had to rely purely on floppy disk development. Roman Ormandy for example was very enthusiastic during the development of Caligari.
c) The fact that it hadn't been done before. It was PFM at the time. Pure Magic.
d) It altered the direction of ASDG. We were a hardware company through and through. The RRD was our first software product and started us towards making software. Almost has fateful as the cab ride I took which completely altered ASDG. But that's a story for another day
Bottom line is that it wasn't so much how well the bear danced, it was that the bear was dancing at all.