[GTALUG] CRT memories [was Re: IBM - cache skirmish story.]

James Knott james.knott at rogers.com
Tue Apr 24 15:25:37 EDT 2018

On 04/24/2018 03:10 PM, D. Hugh Redelmeier via talk wrote:
> First, lets think of a neon tube.  It gets turned on when a high
> voltage is applied.  With no voltage, no light.  But once it has
> started, an intermediate voltage can maintain the light.  If it
> hasn't started, that voltage will leave the tube off.  So, powered by
> that voltage, the tube is a memory.  You can tell its state by the
> amount of current it draws.

Neon lamps have long been known to have a memory effect.  Many years
ago, I worked on an ancient system, made by Teleregister, at the old
Toronto Stock Exchange on Bay St..  It used neon bulbs for some
storage.  It also used a memory drum and flip flops built around 4
vacuum tubes.  One of my first tasks in the morning was to slowly crank
up the filament voltage, for all the vacuum tubes in the system.  I also
had to start a motor/generator set, to provide +/- 130V DC to run it.

Go to the link and search on Teleregister for a description.


That system was installed over a year before I was born!

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