1964 · Transistor Calculator with Screen · Work 923 of 1,871
An engineering office in California, on a side table beside a tilted drafting board a broad pale grey-beige calculator forty-seven centimetres wide with a flat hood jutting forward, in the dark grey face of the hood a small rectangular screen with a soft green glow in four faint horizontal bands, below it a cream keyboard with a square block of nine dark grey keys, a long grey bar, one red key and a small upright thumbwheel at the right, every key plain, smooth and unmarked, a slide rule in a brown leather case laid aside, a hand in a short-sleeved white shirt at the keys, venetian blinds striping the sunlight.
What it was used for
The Friden 130 was one of the first fully transistorized electronic desk calculators. The Smithsonian writes that it went on the market in August 1964 selling for $2,150; by August 1970, according to the Old Calculator Museum, 18,168 had been built. Friden's own 1964 brochure places the machine "midway between the electronic computer and the mechanical desk calculator" and names fields of application, no customers. The price fell to $1,695 effective 27 July 1965; a top electromechanical desk calculator cost about a quarter of the launch price. In Romania ICE Felix built the machine under licence as the CE 30 from about 1970 to 1972/73.
What was new
The 130 showed 4 working registers at once on a cathode ray tube, 13 digits each; Nixie tubes would have been too large and too expensive for 4 rows. That made visible what is now called reverse Polish notation: a stack of 4 levels in which results move upward. Friden's 1964 brochure calls the method "stacking" and "automatic algebraic computations" - the term RPN does not appear in it. Memory was a magnetostrictive delay line, a coiled wire in which the numbers circulated as sound pulses, where the earlier EDTC-1 prototype still had a magnetic drum. According to the Old Calculator Museum, Friden never patented the principle; the patent on the arithmetic logic was held by Mathatronics, and Hewlett-Packard bought it.
What the sources leave open: The sources are silent on use. The kinds of date diverge: prototype demonstration under non-disclosure in June 1963, formal introduction according to the Old Calculator Museum in May 1964 (photo caption), in New York in April 1964 (news page) and at the Waldorf-Astoria in August 1964 (main text), release for sale in August 1964 according to the Smithsonian. No named user and no total transistor count in the sources checked.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.