Neon logic

There's no such thing as an Anita Mk IV(4). The first machine that was sold was the Anita Mk VII, but it was very rare, as it had reliability problems, and was replaced by a redesign called the Mk VIII(8). The Mk VII(7) used three dekatrons along with a slew of cold cathode thyratrons. The Mk VIII dispensed with two of the dekatrons, leaving only one dekatron which was used to scan the keyboard. The counters that performed the counting operations of both machines were made with 10 thyratron ring counters. The ring counters were directly connected to the Nixie tubes, and, in fact, the Nixie tubes were actually an active part of the sequencing of the ring counters. The Nixies were specially designed with the digit cathodes in a specific order to facilitate the jumping of the ring counter The are no heaters used in the thyratron tubes that are present in the Anita Mk 7, Mk 8, or Mk 9 calculators. You can see inside an Mk 8 by going to http://www.geocities.com/oldcalculators/anitaC-VIII.html Rick Bensene The Old Calculator Web Museum http://www.geocities.com/oldcalculators you IBM