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From: Stephen Fuld <sfuld@alumni.cmu.edu.invalid>
Newsgroups: comp.arch
Subject: Re: core memory, Historical evolution of CPU perf
Date: Fri, 11 Oct 2024 16:36:18 -0700
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On 10/11/2024 12:40 PM, John Levine wrote:
> According to BGB  <cr88192@gmail.com>:
>>>> We used the 11/20 as a remote debug device for the 8085 cash
>>>> register machine(s) we were building.
>>>
>>> Core memory: slow to access but also slow to forget.
>>
>> Core memory was before my time, but I remember reading somewhere that it
>> needed to be preheated to a certain operating temperature in order to
>> write to it (because the hysteresis energy of the ferrite rings was
>> temperature dependent, and it needed too much power to flip the bits at
>> lower temperatures).
> 
> The memory for the IBM 7090 in the late 1950s was in a heated oil bath
> but they soon figured out how to make core work at room temperature.
> On the PDP-8 and PDP-11's that I used, the core was in the box with
> everything else with no special temperature controls.
> 

And in the late 1960s and early 1970s the Univac 1108s and the IBM S/360 
models 30 and 65 that I worked with worked just fine in the typical 
cooled computer rooms of the day (IIRC high 60s degrees F)


-- 
  - Stephen Fuld
(e-mail address disguised to prevent spam)