neon tube memories

[Allison]

>
>Subject: Re: neon tube memories
>   From: ard at p850ug1.demon.co.uk (Tony Duell)
>   Date: Thu, 26 May 2005 00:38:52 +0100 (BST)
>     To: cctalk at classiccmp.org
>
>> Unless someone has som ehard data on them being used "digitally"
>> I'd assume the HP counter use was simply as generic, non-switching
>> circuit elements.
>
>The HP5245 counter certainly used neons as memory elements -- I have the 
>instrument and the service manual which has a section on the operation of 
>the counter module.
>
>Each counter module contains 8 transistors wired as 4 bistables. Diode 
>steering is added to make it count either in 1242 BCD code or 1248 (the 
>latter being one of the options available for the instrument).
>
>The collectors of the transistors go to the neons via resistor (and 
>diode?) networks. By varying the voltage on one of the lines you can 
>transfer the state of the counter to the 8 neons and latch it there.
>
>The neons are mounted in a plastic block with a thick-film circuit on 
>top. The thich film elements are CdS photoresistors arranged in a decoder 
>tree which directly drives a nizie tube.
>
>Quite a hack to get a counter, latch and display driver in just 8 
>transistors!


Only takes 4bits to count to 10. Though it could be a switch tail 
ring counter.

>> A write-only neon memory would still make a nice addressable
>> display!
>
>Somewhere I have a neon display which seems to be a dot-matix unit (7 dots 
>high by perhaps 100 long) with transfer electrodes like a Dekatron tube. 
>You apply 7 'bits' to the right hand column, then toggle the transfer 
>electrodes appropriately and all the dots move left one column. Repeat to 
>built up the pattern you want in the display.
>
>-tony

Boroughs Panaplex, I have a 32char version that I power up and it works.
I've designed using the 40 char version pretty cool.  Even got to visit 
the facility in NJ back in '73 where they were made along with the other 
gas tubes (nixe and the like.).

Allison