[time-nuts] tube GPS receivers

[Bob Camp]

Hi

I've both used and worked on core memory machines. They ones I have seen all used solid state devices in the core memory sections of the machine. I've never heard of a pure tube machine with more than "register sized" core.

Bob

On Jun 23, 2013, at 1:47 PM, Chris Albertson <albertson.chris at gmail.com> wrote:

> Magnetic cores were not invented until the 1950's and realy cam into use as
> tubes were beibg replaced by SS.  But there isnot reason yu can't build a
> tube computer with core memory.   I have actually seen and used a computer
> that had one megabyte of core memory.  The stuff was still in use in the
> late 1970s   1MB was a lot of RAM in 1975.
> 
> You can have very good reliability with tube circuits.  It was just that
> few people wanted to pay for it.  Down time was cheaper.  It is not hard to
> add redundancy to a circuit but it does have a huge cost multiplier effect.
> 4x or 5x the price.   One simple way is to use 3 or 4 tubes with their
> output tied to a resistive adder.  If one tube fails the result (because it
> is binary) is still the same.   With computers no one would pay for fault
> tolerant design until it was reasonably affordable.   Even today we mainly
> just put up with failure except for airplane controllers, huge web sites
> like Amazon and the like.
> 
> 
> On Sun, Jun 23, 2013 at 9:53 AM, Brian Alsop <alsopb at nc.rr.com> wrote:
> 
>> On 6/23/2013 14:40, Bob Camp wrote:
>> 
>>> Hi
>>> 
>>> AC137 doesn't ring any bells. True tube core (no solid state at all)
>>> isn't something that was dimensioned in K words. A couple hundred words was
>>> pretty big stuff. "Quite a bit" of core done that way is a lot of tubes. As
>>> the number of tubes goes up, the time to failure comes down….. hours …
>>> minutes … who knows.
>>> 
>>> Bob
>>> 
>>> 
>> Yeah, it gets to be like the cross country aircraft races in the 20's. The
>> mechanic had to fly with the pilot. (The MTBF of many of the engines used
>> was measured in hours.) If necessary he had to climb out on the cowling
>> while in flight to change plugs and fix whatever possible without landing.
>> What would OSHA say about that?
>> 
>> Needless to say future generations will probably find lots of aircraft
>> spark plug artifacts in their digs.
>> 
>> Brian/K3KO
>> 
>> 
>> 
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> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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