How scarce (valuable) is core for the PDP-8?

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Tue Apr 27 11:26:53 1999

><OK, how about it. Put a ring of compasses around the wire with needles str
><enough magnetised that they will stay pointing N-S around the ring regardle
><the Earth's field.
><
><Can you then flip them with a current? A very good visual demonstration of
><core works!
>
> Yep, That would be good to watch but that's really a demo of the fields
> around conductors (imporant building block).

I actually meant to take the demo one step further. Each compass needle has its
own magnetic field. Put them close enough together and (with luck) the N end of
one needle will attract the S end of the other.

Put several of these compases in a ring, and the needles will point around the
ring, whether or not there is a current flowing down a wire in the middle.

And there are two stable states, just like a core.

With (even more) luck, you can flip between states with a current. Just like
core.

Worth a try?

This weekend I shall see if I can find some cheap, small compasses in a toy shop
or somewhere...

Philip.
Received on Tue Apr 27 1999 - 11:26:53 BST