Calculator watch Calculator watch A calculator watch is a digital watch with a built in calculator, usually including buttons on the watch face. Calculator watches were first introduced in the 1970s and continue to be produced, despite falling from their peak popularity during the 1980s. The most notable brand is the Casio Databank series, though watches made by Timex were also popular. Most calculator watches contain only a few number of functions such as +, -, x, / and percents. However, there are several models with additional functions: scientific, including transcendent and trigonometry, in models Casio CFX-200, CFX-400, Citizen 49-9421, and also
History of science and technology in Japan fluorescent display (VFD) and rechargeable NiCad batteries. The EL-8 was the first battery-powered handheld calculator. The concept of a single-chip calculator was conceived by Sharp engineer Tadashi Sasaki in 1968. The first truly pocket-sized electronic calculator was the Busicom LE-120A "HANDY", the first single-chip calculator to be built, released in February 1971. The Busicom 141-PF desktop calculator, released in March 1971, was the first computing machine to use a microprocessor, the 4-bit Intel 4004 (co-designed by Busicom's Masatoshi Shima). In 1971, Tadashi Sasaki began research on the use of LCD displays for calculators at Sharp Corporation. In 1973, Sharp commercially