KBK update for Monday, 13th April
Having finally read through the relevant patent, I now understand how the Mechanical Enterprises Mercutronic coding switch works. (This is the full version of the simpler non-coding mercury type mentioned at Deskthority as an unidentified product.) A detailed diagram of such a switch was posted to Twitter last year by Tube Time, taken from the December 1969 issue of Electronic Engineer magazine (volume 28, no. 12) With luck, it will be possible to get the whole article scanned in by the Linda Hall Library later this year (as and when the staff are able to return to work on premise). When drawing an example diagram of two coding switches I realised that there was a major problem with the design, and that diagram cleared up a point of confusion in the patent about how Mechanical Enterprises addressed it.
Have you ever looked at late 60s and early 70s keyboards and wondered what their large arrangements of diodes are for? These diode matrices are now covered in the first part of the new encoding and output article along with information on self-encoding switches, which made a brief appearance in the late 1960s before disappearing. Only late 60s and early 70s encoding is covered at the moment, which is the important part that I have been keen to document for some time. It would be nice to also document Datanetics’ encoding system, but Meryl Miller appears not to remember how it worked, and it does not appear to have been patented (I only learnt of it from his personal notes). That approach, too, seemed to soon vanish.
To support the above article, there is now a page on Micro Switch KB encoding switches. Additional photographs are due at some point in the future.