>>>>AA6YQ comments below
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Grant
Saviers
Sent: Saturday, July 09, 2016 10:27 PM
To: Ian White; jim@audiosystemsgroup.com; towertalk@contesting.com
Subject: Re: [TowerTalk] AES SK
More OT & re at least a related technology: Long ago, I was involved with the
DEC core memory design and core making. Core making
was an "interesting" operation since the only the "bakers" knew the magic for
getting good cores. Actually only about 30% of every
batch was any good. The good news was the bad cores got ball milled with the
next batch of raw materials, then isostatically
pressed, fired, ground up again, pressed again, fired, and finally ground into
press-able powder, pressed in carbide dies, fired,
and 100% tested. We made billions all for DEC systems and were the last
systems supplier to offer core memory, since real time
systems customers loved never having to wait and wait for a reboot after a
power failure. The last generation cores were 0.012"
OUTside diameter and the all women core stringers in Taiwan put three wires
through each of those tiny donuts. And our core memory
was cheaper to make than DRAMs until after the MOSTEK 64k chip hit its
volume pricing valley. Our ferrite "bakers" were really world class.
DEC bought (cheap) the RCA core memory operation when RCA exited the computer
business in 1971.
When one considers ferrite core memory technology it is a wonder it worked at
all - half select noise, temperature sensitivity,
aging, stress effects, magnetostriction, etc were large engineering and process
control challenges. At least cosmic rays didn't bother it and it
didn't forget and it was the technology that made computers as we know them
possible.
>>>And because DEC made its own core memory, Data General had to make it too. I
>>>designed the Nova 3 to work with up to eight 64
Kbyte core memory circuit boards, each of which sold for what nice cars went
for back in those days.
73,
Dave, AA6YQ
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