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
Sharp EL-8 keycaps are different. Sharp EL-8 The Sharp EL-8, also known as the ELSI-8, was one of the earliest mass-produced hand-held electronic calculators and the first hand-held calculator to be made by Sharp. Introduced around the start of 1971, it was based on Sharp's preceding QT-8D and QT-8B compact desktop calculators and used the same logic circuits, but it was redesigned to fit in a much smaller case. Most electronic calculators before the EL-8 were intended for desktop use. Sharp's predecessor to the EL-8, the battery-powered QT-8B, was just a portable version of a compact desk calculator. The EL-8 was much