The comptometer was the first commercially successful key-driven mechanical calculator, patented in the USA by Dorr E. Felt in 1887.
A key-driven calculator is extremely fast because each key adds or subtracts its value to the accumulator as soon as it is pressed and a skilled operator can enter all of the digits of a number simultaneously, using as many fingers as required, making them sometimes faster to use than electronic calculators. Consequently, in specialized applications, comptometers remained in use in limited numbers into the early 1990s, but with the exception of museum pieces, they have all now been superseded by electronic calculators and computers.
Manufactured without interruption from 1887 to the mid 1970s it was constantly improved; first it was made faster and more reliable, then a line of electro-mechanical models was added in the 1930s, but especially it was the first mechanical calculator to receive an all-electronic calculator engine in 1961, with the ANITA Mark VII model released by Sumlock Comptometer, therefore creating the link in between the mechanical and the electronic calculator industries.
Although the comptometer was primarily an adding machine, it could also do subtractions, multiplication and division. Its keyboard consisted of eight or more columns of nine keys each. Special comptometers with varying key arrays were produced for a variety of special purposes, including calculating currency exchanges, times and Imperial weights. The name comptometer was formerly in wide use as a generic name for this class of calculating machine.
Other articles related to "comptometer, comptometers":
... successful range of key-driven mechanical calculators of the Comptometer type under the names "Plus" and "Sumlock", since the 1930s ... Similar to the Comptometer calculating machines of the time, the ANITA had a full keyboard, a feature that was unique to it and the later Sharp CS-10A among ... then also amalgamated its calculator division with the British operation of Comptometer Corporation of Chicago, U.S.A ...
... patented the Comptometer in 1886 ... The comptometer-type calculator was the first machine to receive an all-electronic calculator engine in 1961 (the ANITA mark VII released by Sumlock comptometer of the UK) ...
... The most important new designs of this period came from the Sumlock comptometer Ltd company that introduced the first all-electronic desktop calculators almost two years ... The last ANITA machine with a Comptometer keyboard was the ANITA mk 10 introduced in 1965, still using cold-cathode switching tubes and that will be ... all transistor desktop calculator, the CS-10A COMPET, introduced in the summer of 1964, also had a Comptometer type keyboard ...
... Felt only sold one hundred comptometers and a few comptographs from 1887 to 1890). 1884 Dorr Felt, of Chicago, developed his Comptometer ... a partnership to manufacture the comptometer in 1887 ...
... Comptometer type calculators were often retained for much longer to be used for adding and listing duties, especially in accounting, since a trained and skilled operator could enter all the digits of a number in one ... The spread of the computer rather than the simple electronic calculator put an end to the Comptometer ...