Monroe Calculators - Overview

Monroe was established in the 1880s and by the middle of the 20th century had become a major American designer and manufacturer of mechanical calculators and office machines. In the 1950s Monroe recognised the beginnings of electronic data processing and entered the computer business with the Monrobot series of small computers. The Monrobot XI computer has a place on this site.

In contrast to some other established calculator companies, Monroe did not overlook or misinterpret the impact that electronics would have on the desk calculator part of its business. In the late 1960s Monroe moved partly into the electronic era with the EPIC calculators. These marvellous machines paired a mechanical keyboard/printer with an electronic calculating unit. They are a crazy hybrid of mechanical and electronic, and unique among first-generation machines - Steampunk may perhaps have been invented by Monroe in the 1960s.

Monroe did not pursue further in-house development of electronic calculators and instead embarked on a series of OEM agreements where outside maufactureres supplied Monroe-branded machines for sale:

  • Olympia of West Germany
  • Canon of Japan
  • Compucorp of California.

Compucorp are noteworthy among third-generation calculator manufacturers for being one of the first to develop a microprogrammable LSI chipset for calculators. The same chipset could be microprogrammed for a general or a special application, allowing Monroe to market special-purpose calculators for niche markets e.g. banking and bond trading.

Monroe remains in the calculator and office machine business to this day, currently as a reseller of OEM calculators and office equipment.

Monroe 770 by Olympia

This is the first fully electronic calculator bearing the Monroe name, following on from the hybrid EPIC electromechanical machines. The Monroe 770 is a first-generation all-transistor machine with core memory. The User Manual available in the Data section has a copyright date of 1968.

The 770 is actually a rebadged Olympia RAE 430-2 and was designed and manufactured by Olympia in West Germany. In the late 1960s Olympia machines were sold in the US under the Monroe name.

All further information relevant to the Monroe 770 is in the Olympia RAE 4 / 30-2 entry.


Monroe 950 by Canon

Monroe 950
The Monroe 950 is a second-generation machine with SSI IC’s and delay line memory. It is actually a rebadged Canon, designed and manufactured by in Japan. The rapid advance of the Japanese electronics industry in the late 1960s is evident as Monroe moved from Europe to Japan as a source of OEM calculators.




Monroe seems to have taken a closer interest in its calculator business than simply buying and reselling OEM machines because the relationship with Canon lasted only a few years, being replaced by the far more sophisticated LSI machines that were developed by Compucorp in the USA. These Monroe-branded machines appear to have had a long life in their niche markets and would have protected Monroe from the fierce competition in the basic calculator market.

Monroe Systems remains in the calculator and office machine business to this day, currently as a reseller of OEM calculators and office equipment.