20 Nov
1998
20 Nov
'98
6:05 a.m.
Ethan wrote:
At least the old cores are embedded
in some kind of pliable substrate (hot glue?)
Since the cores are fragile, that serves to protect them from mechanical
stress, in handling, and perhaps in operation. I don't know to what extent
it affects 18/30 and smaller cores, but there were problems with larger cores
vibrating in operation.
Of course, it took a lot of amps to switch the big cores, so they also had
problems with heating due to the power dissipation. And the hysteresis
curves of the big cores were more temperature sensitive, so the stack
had to be maintained at a constant temperature. Some early core systems
like the IBM 7302 (used on the 7090) were immersed in oil for this reason.
The later 7302A was apparently air-cooled.