core... more

From: Allison J Parent <allisonp_at_world.std.com>
Date: Thu May 6 21:43:28 1999

Well thanks to John D. I have a bunch of cores from the early 60s.

They are roughly 50mils x 11 mils x 15mils. Cross section of the doughnut
is rectangular at 15x11 mils. The reason for such rough measurements is my
vernier is only good to .001" and I'd need somthing fancier to be more
accurate. By eyeball the 8e cores are smaller! Based on several articles
I've read theses will need about 400->600ma to switch and will do so in
under 4uS. I will have to test this in a jig. Since the hole is ~20mils
several #40 wires should pass through it easily.

A simple core frame would be 8x8 (64 bits) and use a 4 wire system as
that simplifies the select, inhibit and sense hardware. I'd likely go
with late 70s level TTL and transistors to drive these and to sense the
outputs I don't know if I'll use transistors (1968 or earlier designs) or
comparator chips (aka 1540, 710, 711) will be used. They would also be
consistant with 1970s technology. The goal if I can get the time is a
64x8 or 64x12 memory. Not large but enough. Why 64? becuase 1 of 8
decoders were common even in 1970, and the larger the array the more
noise from switching. So 8x8 is manageable.

Allison
Received on Thu May 06 1999 - 21:43:28 BST