Talk:Selectron tube

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The article states "To select a bit to be read from or written to, all but two adjacent wires on each of the two grids were biased negative, allowing current to flow to the dielectric at one location only".

This does not match the operation described in an old Astounding Science Fiction science column I read many years ago, in the Cambridge University Science Fiction Society's collection (sorry, I can't be more specific).

Found it! Well, the volume, not the story...yet: Modern Calculators by E. L. Locke; in January, 1949; Volume XLII, No. 5. OldZeb (talk) 06:11, 14 December 2007 (UTC)[reply]

Perhaps it was a later variant of the device, since the column was from the '50s. Anyhow, in that the wires were actually strips edge on to the electron spray, and they were linked up in a way that used the properties of numbers to make only one adjacent pair have positive bias even though many strips shared each control signal, rather like Moire fringes. If an adjacent pair had negative bias, nothing would get through from the usual grid effect, and if the pair had opposite sign the electrons would be pulled aside onto the positive strip and not get through that way. This arrangement meant that the total number of bits didn't end up a power of two, but you could use far fewer control signals and so fewer circuits to select them.

If anyone else can confirm this and rewrite that more clearly than I can, I would suggest altering the main article here to match. Oh, and maybe people can cross-refer this to the somewhat similar Sony Trinitron colour TV system. P.M.Lawrence 203.220.81.189 09:13, 20 September 2007 (UTC)[reply]

Hi P.M.; Your memory is correct. My edits tried not to get too much into the detail of Geo. W. Brown's clever decoding scheme as it is covered well in the external links. I have trouble with deciding how much detail embraces the "encyclopedia" format as opposed to the textbook format. If you want to give it a try, my www.rcaselectron.com site has all the original documentation. The selection-by-deflection gating scheme is very similar to that of the Chromatron Tube of E. O. Lawrence. (A relative?) Thanks for your input. (s.) Charles OldZeb 04:58, 11 November 2007 (UTC)[reply]