Interton PC 4020

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Interton Electronic has been manufacturing the PC 4000 series of calculators since 1974. These used the widest range of circuits available in that era, and their display was built from LED-sticks which was absolutely dominant that days. The drastic fall in prices has led the manufacturer to produce simpler, cheaper models that were more powerful than the competition. In 1975, the new 4000 series models — as well as the new version of the PC 4009 — appeared in the same housing as before, but already with cheaper Japanese Itron VFD display tubes, which produce greater and brighter digits than LEDs. All four models had MOS Technologies chips, 7541 007 in the 4009, 4010, and 4020; and 7529 014 in the scientific model 4030. The first three versions differed only in their keyboard: the 4009 had the same functionality as the previous series, and the only difference between the 4010 and 4020 was that the former did not have memory functions available; otherwise, both models had a sign change, square root, square, and reciprocal key, and can specify the number of decimal places for rounding the results. The machines were still in production the following year. Due to further cost reductions, the keyboards were replaced with products from the Japanese JELCO factory, but as Interton saw that they could not make calculators profitably in the future, they decided to cease calculator business completely.