Calculator watch financial functions (in the Casio CBA-10). Usually calculator watch operates with eight digits number, however, calculator watch can operate with 6 digits (for example, Casio C-801) or 10 digits (Casio CBA-10) numbers. Calculator watches first appeared in the mid 1970s introduced by Pulsar (1975, then a brand of the Hamilton Watch Company) and Hewlett Packard. Several watch manufacturers have made calculator watches over the years, such as Pulsar and Timex, but the Japanese electronics company Casio produced the largest variety of models. In the mid-1980s, Casio created the Databank calculator watch, which not only performed calculator functions, but also stored
Marchant calculator known as SCM, tried to stay competitive by introducing the SCM Cogito 240SR electronic calculator (designed by Manhattan Project veteran Stan Frankel) in 1965. Within a few years a tidal wave of cheaper electronic calculators had devastated their business, and by the mid-1980s, SCM's typewriter business, too, had been ruined by the advent of inexpensive personal computers used as word processors. The first Marchant calculators differed greatly from their later Silent Speed Proportional Gears machines, which were by far the fastest of their type, running at 1,300 cycles per minute. These machines are of considerable technical interest, and are far