imitation game movie

Jon Elson elson at
Wed Feb 11 12:51:13 CST 2015

On 02/11/2015 12:38 AM, Chuck Guzis wrote:
> On 02/10/2015 09:56 PM, Jon Elson wrote:
>> Oh, absolutely!  There was a lot of work on using ferrite 
>> rings as storage
>> and logic elements at that time, but Forrester and Papian 
>> really
>> extended what had been done before, and the coincident 
>> current
>> scheme was really ELEGANT and made large arrays of fast 
>> memory
>> practical.  The bigger you built the array, the more 
>> memory you got
>> with small increments in the number of drivers.
> Didn't coincident-current relays come before that (as 
> used, for example, in telephone switching equipment)?  So 
> the basic idea was there.
I'm sure not aware of that.  #2 ESS uses ferreed switching 
elements, but it was WAY after
core memory was developed.  The original core design was 
done somewhere around
1948 - 1950, I can't find an exact reference.  I'm unaware 
of any similar, entirely
electrical/magnetic latching scheme used in telephony that 
predates that.  Western
Electric crossbar was quite mechanical although it did use a 
matrix scheme to
select crossbar contacts to opened or closed.
> I've always been fascinated by magnetic core logic; both 
> using "hard" magnetics (e.g. Univac SS) and "soft" (e.g. 
> Parametrons).  I wonder if magnetic core for memory hadn't 
> been developed, would we have developed electrostatic or 
> some other technology to the same density?
> Would we have developed ultra-fast recirculating memory?
I'm sure memory technology could have gone a number of 
different ways.  i don't
think classic core memory could NOT have been developed, it 
is too marvelous
for people to have missed the concept for much longer.

There were some other schemes, twistor and plated wire 
memory, and biax memory.
Some of these were non-volatile, which was an advantage to 
the military.  But,
one of those technologies could have become dominant, instead.

I never understood why bubble memory didn't continue to 
progress. Vertical
Bloch line memory might have eventually developed to the 
capacity of
modern flash memories, and probably not had the wear-out 
They never would have reached the read performance of flash, 
but might
have kept up with the write performance.

Hmmm, flash memory IS really electrostatic.  And, a lot 
better than anything
like Williams tubes.  I guess old-style DRAM was basically a 
silicon implementation
of a Williams tube!


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