Comptometer - Comptometer Corporation

The Felt & Tarrant Mfg Co became public in 1947 and changed its name to the Comptometer Corporation in 1957.

Comptometer - Comptometer and comptograph

Forty years later, in the mid-1950s, the Comptometer Corporation reused the name Comptograph for a line of 10 key printing machines.

Comptometer - Comptometer and comptograph

Two years later, on June 11, 1889, he was granted a patent for the Comptograph. A Comptograph is a comptometer with a printing mechanism making it more like a key-set calculating machine (even though the keys are registered as they are typed and not when a handle is pulled), therefore slower and more complicated to operate. It was the first printing-adding machine design to use individualized type impression which made its printed output very legible.

Comptometer - Comptometer and comptograph

The original comptometer design was patented by Felt, on July 19, 1887 and on October 11, 1887.

Comptometer - Victor Comptometer Corporation

In 1961, the Comptometer Corporation merged with the Victor Adding Machine Company, and the two became the Victor Comptometer Corporation. After barely surviving the microprocessor revolution, it is still doing business today as Victor Technology LLC.

Comptometer - Bell Punch Company – Sumlock Comptometer Ltd

In 1960, the Bell Punch Company bought the British rights to the Comptometer design and trademark, and continued its development. In 1961, Sumlock, a division of the Bell Punch Company, was renamed The Sumlock Comptometer Ltd, and began marketing the first all-electronic desktop calculator, the ANITA Mark VII. The entire calculator division of the Bell Punch Company was bought by Rockwell International in 1973. They exited the calculator business in 1976 and shut down all operations.

Comptometer - Model F

The production of this model started in 1915 and lasted five years. The error detection mechanism is moved inside the box and the release key is red. This machine is the last machine without the Comptometer logo inscribed on its front and back panels.

Comptometer - Competition

The comptometer was the first machine in production to challenge the supremacy of the arithmometer and its clones; but not immediately, it took almost three years to sell the first hundred machines.

Comptometer - Post World War II models

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 before the competition. They were the ANITA Mark VII, first introduced in 1961 and marketed in Continental Europe and the ANITA Mark VIII, a slightly improved design, introduced at the same time, marketed in Britain and the rest of the world. They both started shipping in 1962.


The comptometer was the first commercially successful key-driven mechanical calculator, patented in the United States by Dorr E. Felt in 1887.

Comptometer - Post World War II models

Sharp's first all transistor desktop calculator, the CS-10A COMPET, introduced in the summer of 1964, also had a Comptometer type keyboard.

Comptometer - The first comptometers

Dorr Felt began his work on comptometer in 1882 and started building first prototype during the American Thanksgiving holidays of 1884. Because of his limited amount of money, he used a macaroni box for the outside box, and skewers, staples and rubber bands for the mechanism inside. It was finished soon after New Year's Day, 1885. This prototype, called the macaroni box, is in the Smithsonian Institution in Washington, D.C., United States.

Comptometer - Model H, J, ST

Manufactured from 1920 until the beginning of World War II, these models incorporate all of the improvements of the previous machines. The Comptometer logo is inscribed on their front and back panels and they have the red release key that was introduced with the previous two models.


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.

Comptometer - Origins

The comptometer is the direct descendant of the key-driven machine of Thomas Hill patented in the United States in 1857 and of the Pascaline invented by Blaise Pascal in France in 1642. By just replacing the input wheels of the Pascaline by the columns of keys of Hill's machine, the comptometer was invented. Addition is performed exactly the same way, and both the Pascaline and the Comptometer make use of the 9's complement method for subtraction, but in the case of the comptometer it is the operator who must choose the right keys for the subtrahend (each key has its 9's complement written in miniature letter next to it).

Comptometer - Post World War II models

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 replaced in 1968 by the ANITA mk 11, a 10 key machine.

Sumlock ANITA calculator - History of ANITA calculators

In 1966 the calculator manufacturing operation of the Bell Punch Company was formed into a separate company, called Sumlock-Anita Electronics, and continued to manufacture both the mechanical and electronic calculators, still marketed by its Sumlock Comptometer division.

Mechanical calculator - The end of an era

Mechanical calculators continued to be sold, though in rapidly decreasing numbers, into the early 1970s, with many of the manufacturers closing down or being taken over. 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 movement of the hands on a Comptometer quicker than was possible serially with a 10-key electronic calculator. In fact, it was quicker to enter larger digits in two strokes using only the lower-numbered keys; for instance, a 9 would be entered as 4 followed by 5. Some key-driven calculators had keys for every column, but only 1 through 5; they were correspondingly compact. The spread of the computer rather than the simple electronic calculator put an end to the Comptometer. Also, by the end of the 1970s, the slide rule had become obsolete.

Motorola 6800 - Development team

Tom Bennett had a background in industrial controls and had worked for Victor Comptometer in the 1960s designing the first electronic calculator to use MOS ICs, the Victor 3900. In May 1969 Ted Hoff showed Bennett early diagrams of the Intel 4004 to see if it would meet their calculator needs. Bennett joined Motorola in 1971 to design calculator ICs. He was soon assigned as the chief architect of the microprocessor project that produced the 6800. Others have taken credit for designing the 6800. In September 1975 Robert H. Cushman, EDN magazine's microprocessor editor, interviewed Chuck Peddle about MOS Technology's new 6502 microprocessor. Cushman then asked "Tom Bennett, master architect of the 6800", to comment about this new competitor. After the 6800 project Bennett worked on automotive applications and Motorola became a major supplier of microprocessors used in automobiles.

Victor Technology - Company history

A. C. began to evaluate the computer market during the 1950s. He decided that the market had potential, but that he would stay out of it until he could find or develop a product suitable for both large and small businesses. The solution came in 1961 when Victor merged with the Comptometer Corporation, which produced calculating machines and a telecommunication device called the Electrowriter.