Monroe - 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 has a place on this site.

In contrast to some other established office calculator companies, Monroe did not overlook or misunderstand the impact that electronic logic would have on the desk calculator part of its business. In the 1960s Monroe pursed a variety of in-house and external desk calculator developments including:

  • In-house development of the EPIC series of hybrid programmable calculators.
    These marvellous machines used a mechanical keyboard and printer with an electronic calculating & logic unit and magnetostrictive wire memory.
    The author once had one of these machines but sadly, no more. He'd very much like to find another...
  • OEM agreement with Olympia from Germany
  • OEM agreement with Canon of Japan
  • OEM agreement with Compucorp of California.
    Compucorp were one of the first to develop a microprogrammable LSI chipset for calculators. This chipset could be microprogrammed for any desired general or special application, allowing Monroe to market special-purpose calculators for specific niche markets e.g. banking and bond trading.

It appears that Monroe did not continue in-house development of calculators after the EPIC series, but instead marketed OEM versions of machines from Olympia, Canon and then finally, Compucorp.

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

Monroe Catalog


Monroe 770 by Olympia

This would be the first fully electronic calculator bearing the Monroe name, following on from the EPIC electromechanical machines. The User Manual available in the Data section has a copyright date of 1968.

The Monroe 770 is a first-generation all-transistor machine with core memory. It is actually a rebadged Olympia RAE 4/30-2 and was designed and manufactured by Olympia in West Germany. In the late 1960s Monroe sold these machines in the US under the Monroe name.

A Monroe 770 User Manual is available in the Data section.

All further information on the Monroe 770 is available at the Olympia RAE 4/30-2 entry.

Monroe 950 by Canon

This is a second generation machine with SSI ICs.

The Monroe 950 was actually designed and produced by Canon under an OEM arrangement with Monroe. The Monroe 950 is based on the Canon 141 but the Monroe is an improved version. In particular, the Monroe has conventional display of negative numbers rather than the tens complement representation of the Canon 141.