Actually, I think it's so you can't drop them down the hole.

This is the reason. Kevin -- Kevin McQuiggin VE7ZD mcquiggi(a)sfu.ca

I'm looking to acquire a core stack (operable - not just to look at) for a construction project (don't ask - if it works I'll report to the list later!) By way of trade, I have a genuine S-100 8K core memory (I forget the manufacturer - the only one made for the S-100 as I recall, though.) If there are interested parties, I'll look it up and tell you the maker and serial number. I'd like to trade it for at least a 16K word by 16 bit stack or plane assembly - just the core - I do not need the electronics. The core needs to be around a 1 uS (20 to 30 mil?) variety and also needs to be 3d (X-Y + sense + inhibit) or four-wire design. I prefer a "stack" or "cube" design, but a planar layout is ok, too. For information, the S-100 core is planar and some of the smallest and fastest core I've seen. It is mounted on a single (fairly thick) S-100 card, with electronics and I believe it to be in working order. (I actually *used* one of these types of cards many years ago on a building HVAC management system that needed "nonvolatility" but the ability to read/write while operating.) It ran without hitch on a 4 mhz Z80 Cromemco system. The unit I'm offering to trade came from a surplus electronics place and I have not (yet) tried it to see if it works. It was lovingly packed in bubble wrap, so I assume the original seller thought better than to just toss into the "heap." Please reply by private email. Thanks.