Memory like... like... one of those metal things with holes in it.

I was going to post a query because it was one of those things that you couldn't Google, and that wouldn't be on Hal Hall's SFRDB, nor in the Locus Index (which I find answers most things round here).

Only I've forgotten what it was.

If anyone a) knows what it is and b) what the answer was, I'd appreciate it.