On 2015-Oct-29, at 10:22 AM, Jon Elson wrote:
On 10/28/2015 11:48 PM, Brent Hilpert wrote:
> Very interesting to hear of another scheme, but it's not clear whether it applies
to the Gemini auction memory. The BiAX scheme shows cores with the holes (apertures as
they're called in the business) perpendicular to each other. In contrast, the Gemini
auction cores have two apertures with the same orientation (a figure 8).
Yes, but I'm pretty sure the concepts are related.
The remanent flux in the non-volatile side of the core affects the flux hysteresis in the
volatile side, so when you flip the flux polarity on the volatile side, you can see some
effect caused by the non-volatile side.
At a general level, as you suggest, they could be said to be related, however what
description is out there does seem to indicate them being distinct in the detail.
Refs on this page:
refers to the Gemini memory as being of the MARS type "Multi-Aperture Readout
MARS is described here if one wishes to delve into the magnetics:
A cursory description of BiAX
does describe different functional principles as suggested in one sentence here:
Photos of the Gemini auction memory:
See the third photo for detail.
. . and a photo of BiAX cores:
While researching this I ran across a couple of other patents for multi-aperture
A fair effort seems to have been put into developing a non-desctructive readout for core
memory, to little effect in the marketplace. Looking at the photos one can see why, it
looks like the methods doubled or better the complexity of construction, so the
'standard' core memory techniques remained the most cost-effective.
Amusingly, there was also a magnetic core device called a "transfluxor". Take
that, flux capacitor.
I like this one however, another technique for NDRO, using standard core construction,
from the 50s:
The magnetised core acts as a non-linear mixing element for two RF signals sent down the
The magnetic polarisation of the selected core affects the mixing in such a manner that
the phase of the difference/beat frequency can be observed to determine the polarisation
and hence the stored-bit contents.