> On Jan 6, 2022, at 4:06 AM, Brent Hilpert via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
>> Not cost effective at nearly $10,000! I understand they're very rare, given
>> they were only used for a few years in industry and they're clocking on 3/4
>> of a century old, but even then, that seems an order of magnitude or two off
>> the real value.
>> Actually, looking them up, doesn't seem they were used in much at all. Seems
>> to have been a bit of a technological dead-end since core memory quickly
>> superseded it with it's (relatively) cheap costs and (relative) ease of
>> manufacturing. I imagine the US gov. probably used them somewhere, since
>> they were a sucker for cutting edge technology of the time.
>> Would be interesting to know how many hours it's got on it
>
> "Not cost effective" ? What does that mean in the arena of valuation of
> historic artifacts?
>
> No, they didn't go anywhere as a product and apparently only saw use in one
> machine.
>
> However, the 'pro' side of such a debate is that they were a very early
> attempt to produce a fast digital RAM memory specifically for use in
> Stored-Program Machines, at a time when memory was at the top of the list of
> problems in development of the first SPMs, and actually before any SPMs had
> been produced, and weren't a serial technology like drums and delays lines
> tortured into applicability for the task.
Yes, for example in van Wijngaarden's 1948 course text "principles of
electronic calculating machines", the Selectron is explained in detail (as a 4k
bit device, which apparently was the original hope). It also mentions
something like a Williams tube (not by that name, so perhaps it's not exactly
that). The only other idea for a random-access RAM that it mentions is a
rather vague notion that a crossbar of gas discharge elements could be used.
That was later (1960) used as a display device, the famous plasma panel display
invented by Don Bitzer et al.; not clear if it was ever actually used as a
memory device. Core memory does not appear in that 1948 document, that's a
later invention but indeed the one that ended up successful in practice.
paul
