On Thursday, May 06, 1999 9:43 PM, allisonp_at_world.std.com
[SMTP:allisonp_at_world.std.com] wrote:
> 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!
According to Pugh's "IBM's 360 and Early 370 Computers", in 1963 IBM was
manufacturing both 30x50 mil and 19x32 mil cores (inside diameter x outside
diameter). Allison's measurements match up with the larger size.
According to the book, the IBM 7080 and 7094 used the smaller size. Thus,
these cores were probably intended for either the 1401, or the 7090 if any of
these were still in production in 1963.
Does anyone out there have a 1401, or a 1401 core stack?
Something I hadn't read of before: the 7090's core planes were immersed in oil
to help with heat dissipation. I wonder whether there was a sticker on the
machine (right underneath "Trained Service Personel Only"): "Change oil every
six months or 100,000 punched cards".
Another interesting point: The defect ratio of cores that reached the plane
wiring stage was 1 out of 8,000. This sounds incredibly high, but IBM's core
manufacturing facilities were state of the art. Imagine the difference between
the process control used then, and current integrated circuit fabrication
techniques!
> 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.
I'd very much like to see your schematics, once you're happy with them. Better
late than never to learn about appropriate circuit designs.
----
John Dykstra jdykstra_at_nortelnetworks.com
Principal Software Architect voice: ESN 454-1604
Enterprise Solutions fax: ESN 667-8549
Received on Fri May 07 1999 - 09:00:12 BST