3 Feb
2023
3 Feb
'23
4:19 p.m.
On 2/3/23 08:25, Paul Koning via cctalk wrote:
It's puzzling that temperature would matter. Obviously, when you hit the Curie
temperature the data goes away, but for typical magnetic materials that is in the hundreds
of degrees. Does the hysteresis curve shift enough at moderate temperatures (a bit over
room temperature) to matter?
Yes, it does. Maybe on earlier memories it was worse, but
most later core systems had a thermistor in the core plane,
and it adjusted the half-select current to put it right in
the middle of the range of susceptance (is that the right
term?) for that temperature.
My recollection is the 1620 had the core planes in a tank of
oil, and the 360/50 had a heater in the air stream flowing
past the local store core stack.
Jon