Monroe Calculating Machine Company

History

In 1911, Jay Randolph Monroe first saw the Baldwin Calculator, the invention of Frank Stephen Baldwin. Although Mr. Baldwin's machine had been patented in 1874 and had been judged by the Franklin Institute as the most noteworthy invention of that year winning the John Scott Medal, it had not been developed for commercial use. Mr. Monroe recognized the merits of the Baldwin Calculator, and in April 1912 he organized the Monroe Calculating Machine Company, and in a small rented room near Newark, New Jersey, the manufacture of the first Monroe Adding-Calculator was begun.

The following year the firm moved to Orange, New Jersey. The factory personnel consisted of only nine men and the entire heavy factory equipment was a lathe and two small presses. Even with these meager tools, tolerances were maintained to within thousandths of an inch to insure the accurate performance of the finished machine. The first Monroe was offered to the business world in 1914.

In 1932, the company was awarded the Franklin Institute's John Price Wetherill Medal.

For many years, Monroe was headquartered in Orange, New Jersey and Morris Plains, New Jersey with its manufacturing plants in New Jersey, Bristol, Virginia and Amsterdam. In 1958, the company was acquired by Litton Industries. Litton sold it in 1984. In the mid-1980s, the company diversified and began carrying a line of private-labeled copiers (manufactured by Mita Corp.) and cross-cut paper shredders, but those items have been discontinued.

In the 1970s and 1980s, the company had some 300 sales and service branch offices in the United States. In 1972, Monroe announced a pocket-sized electronic display calculator at $269. As low cost electronic calculators from Japan became readily available through retail distribution, the mechanical calculator companies like Monroe, Friden, and Marchant declined even as they introduced programmable calculators.

Mechanical and Electromechanical Calculators

Early models of calculator were designated by letters. The letters A, B, and C are lost in the records of those early days devoted to constructing a suitable pilot model. The "D" model started manufacture in 1915 with serial numbers below 4,000. The "E" model started manufacture in 1916 with serial numbers beginning at 4,000. The "F" model was introduced in 1917 with serial numbers above 6,000. The "G" model was the first machine of the refined style, and was introduced in 1919 with serial numbers above 20,000. The "H" and "I" were never released for production. The "K" was the real start of the big forward march by the Monroe Company. The "K" hand machine, introduced in 1921, was followed by KA, KAS, KAA, KASC, KASE, etc., machines all more fully automatic than the former. The "L" model was produced from January 1929 to February 1971. The "M" model further refined the "L".

Electromechanical models; rotary calculator display models and printing models

Model 145 was the last adding machine model produced. Model 570 was the last electro-mechanical four-function calculator model produced.

Electronic Calculators

Electronic calculator models

Visual Display only Paper tape and visual display

Programmable models

The 1600 and 1800 series calculators, from OEM Compucorp competed against similar desktop calculators from Wang Laboratories. Model 200 billing machine for accounts receivable functions. Monroe Calculating Machine Mark XI (or "Monrobot XI") was an inexpensive, relatively slow, general-purpose computer introduced in 1960