Greybeards (Re: Netbooks & BSD)
Henry Olyer
henry.olyer at gmail.com
Thu Oct 21 17:27:46 UTC 2010
My first machine was an IBM 1620, but hey, at least we had an actual disk.
A couple of 2311's.
To quote a fellow I used to consult for, two days' I had solved a
particularly nasty programming problem for his company, "But what have you
done for us lately?"
On Thu, Oct 21, 2010 at 10:57 AM, RW <rwmaillists at googlemail.com> wrote:
> On Thu, 21 Oct 2010 14:32:23 +0100
> Arthur Chance <freebsd at qeng-ho.org> wrote:
>
> > On 10/21/10 13:38, RW wrote:
> > > On Wed, 20 Oct 2010 21:10:28 +0100
> > > Arthur Chance<freebsd at qeng-ho.org> wrote:
> > >
> > >
> > >> 50s) had the experience of programming microcode on a machine by
> > >> inserting brass slugs for 0s and ferrite slugs for 1s on a pin
> > >> board.
> > >
> > > I wonder why it was brass/ferrite rather than brass/empty or
> > > ferrite/empty.
> >
> > Dredging up physics unused for 30+ years, ferrite is ferromagnetic
> > and intensifies magnetic fields so a coil of wire with ferrite inside
> > is a massively bigger inductor then an empty coil. I vaguely remember
> > that brass is slightly diamagnetic, but could be mistaken. If it is,
> > then it would have the opposite effect and reduce the inductance, so
> > you'd get a better difference in signal between brass/ferrite than
> > air/ferrite.
>
> Possibly. I'm wondering if there might be three states, where the third
> state is writable.
>
> > Air/brass would give very small differences in signal,
>
> I was thinking in that case it would be open/short circuit.
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