Ring vs BCD counters for decades

The first electronic calculator, the Anita Mk 7, used 10-stage thyraton-based ring counters. The machine was essentially an electronic implementation of an electromechanical calculator. The ring counters were of a very unusual design, developed by Norbert Kitz, who was a master of thyratron circuitry, and also a major proponent of pure 1-of-10 (decimal) representation for use in electronic calculating machines. He said at one point in a paper referring to his design ideas something to the effect (can't remember the exact quote at this moment) at "no silly binary is needed here". The ring counters connected directly to the Nixie tube for the display. The Nixie tube was an active part of the counter advancing circuitry, such that the digits were "stacked" in the Nixie in a special order to allow the firing and shutdown of the nixie digits to stabilize the ring counter such that it would step very reliably one count at a time (even at relatively high clocking rates for thyratron circuity), as thyratrons were a bit picky as far as circuit parametrics went. The design was quite brilliant, and very efficient, as absolutely no decoding was needed at all...the 10-thyraton ring counter and the Nixie tube worked together synergistically. The Nixie tubes were custom-designed for this circuitry. If someone has one of these old machines (Anita Mk7, Mk8, and Mk9), and a Nixie is bad, an exact replacement has to be found, as not just any Nixie tube will work. The Mk7 calculator was made in very limited production, as it had some stability issues, which were refined in the Mk8 (and the overall circuitry simplified a bit). The Mk8 was quite widely marketed, and successful. I have an exhibit on the Mark 8 on my Old Calculator Museum website (a schematic of a digit stage is included there) at http://oldcalculatormuseum.com/anitaC-VIII.html While thyratrons are much different than vacuum tubes, the Sumlock/Anita calculators based on this technology were quite amazing for their time (introduced in 1961), and on their own, created an entire new market...the electronic calculator. Rick Bensene The Old Calculator Web Museum http://oldcalculatormuseum.com