Burroughs Corporation

In 1886, the American Arithmometer Company was established in St. Louis, Missouri, to produce and sell an adding machine invented by William Seward Burroughs (grandfather of Beat Generation author William S. Burroughs). In 1904, six years after Burroughs's death, the company moved to Detroit and changed its name to the Burroughs Adding Machine Company. It was soon the biggest adding machine company in America.

The adding machine range began with the basic, hand-cranked Class 1 which was only capable of adding. The design included some revolutionary features, foremost of which was the dashpot which governed the speed at which the operating lever could be pulled so allowing the mechanism to operate consistently correctly. The machine also had a full-keyboard with a separate column of keys 1 to 9 for each decade where the keys latch when pressed, with interlocking which prevented more than one key in any decade from being latched. The latching allowed the operator to quickly check that the correct number had been entered before pulling the operating lever. The numbers entered and the final total were printed on a roll of paper at the rear, so there was no danger of the operator writing down the wrong answer and there was a copy of the calculation which could be checked later if necessary.

The Class 2 machine, called the "duplex" and built in the same basic style, provided a means of keeping two separate totals. The Class 6 machine was built for bookkeeping work and provided the ability for direct subtraction.

Burroughs released the Class 3 and Class 4 adding machines which were built after the purchase of the Pike Adding Machine Company around 1910. These machines provided a significant improvement over the older models because operators could view the printing on the paper tape. The machines were called "the visible" for this improvement.

In 1925 Burroughs released a much smaller machine called "the portable". Two models were released, the Class 8 (without subtraction) and the Class 9 with subtraction capability. Later models continued to be released with the P600 and top-of-the-range P612 offered some limited programmability based upon the position of the movable carriage. The range was further extended by the inclusion of the Series J ten-key machines which provided a single finger calculation facility, and the Class 5 (later called Series C) key-driven calculators in both manual and electrical assisted comptometers.

In September 1986, Burroughs Corporation merged with Sperry Corporation to form Unisys. For a time, the combined company retained the Burroughs processors as the A- and V-systems lines. As the market for large systems shifted from proprietary architectures to common servers, the company eventually dropped the V-Series line, although customers continued to use V-series systems as of 2010. As of 2017 Unisys continues to develop and market the A-Series, now known as ClearPath.