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

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Thu Apr 22 12:01:25 1999

read to end...

On Thu, 22 Apr 1999, Dave Dameron wrote:

> At 08:49 AM 4/22/99 -0400, Allison wrote:
> >> >Cores large enough for visual indication of magnetic field would be in the
> >> >10-20AMPS select curent range. Not a real possibility.
> >>
> >> Maybe so, but those are practicality issues, not feasibility.
> >
> >that answer equates to "whatever". Describe the mechanics of displaying
> >the orientation of a magnetic field in a closed torus? I was trying to
> >get someone to think on how thjis may be done impractical or not.
> >
> Yea, the field lines are contained inside the toroid, no external poles.
> For an *exotic* way, the
> Aharonov-Bohm effect might work. See the Scientific American article, April
> 1989. This, by the way, is that the magnetic potential is outside the torus
> and can effect an electron in the quantum realm. Of course the effort and
> equipment to do this for 1 bit would overwhelm the rest of the machine!
> More on topic, the magnetic cores they used were 5 microns in diameter and
> ferromagnetic, not "ferroelectric". They were 83% Ni and 17% iron, on a
> silicon wafer, also shielded by niobium.
> -Dave
>

then there is the easy way... apply a magnetic field and see if it
switches.

Allison
Received on Thu Apr 22 1999 - 12:01:25 BST