Monroe Nixie Tube Calculator

Physics

Accession Number: 2014.ph.631

Instrument Name: Monroe Nixie Tube Calculator

Description:

The Monroe Nixie Tube Calculator is a plastic instrument that has components in both an off-white color and a dark brown/black color. The front of the instrument consists of a box-like shape with a large portion cut away to make an “L” shape when viewed from the side. Vent holes in a grid shape have been cut into the plastic in the top of the instrument. On the front of the machine there is a display face for the numbers, which are housed in 14 glass tubes. The glass tubes are housed behind the plastic face. Directly below but perpendicular is a number and function key pad used for the operation of the instrument. Most of the instrument’s control panel and face is a dark brown/black hard plastic. The sides, top and back of the instrument are an off-white hard plastic. The base of the instrument is a hard dark brown/black plastic with more vent holes cut into it and two metal labels. There is a grey electrical cord for the calculator which plugs the instrument into the wall in order to be able to operate the calculator.

Alternative Name: Scientific Calculator

Primary Materials:

Plastic, Glass, Electrical Components, Wire Filaments, Computer Circuits

Markings:

Two metal labels are found on the bottom of the instrument.

Top label:
“CAUTION TO PREVENT SHOCK DO NOT REMOVE COVER NO USER SERVICEABLE PARTS INSIDE REFER SERVICING TO QUALIFIED SERVICE PERSONNEL”

Bottom label:
“MONROE A DIVISION OF LITTON INDUSTRIES MODEL 1655 NO E 915866 NON INTERFERENCE AC 115V 60W 50-60 Hz REG US PAT OFF MARCA REG MADE IN USA”

Dimensions (cm): Height=17, Width= 32, Length= 34.5

Function:

The instrument is a programmable scientific calculator. It allows mathematical computing, usually at a sophisticated level, without the need to work the calculations out by hand. This calculator is part of the transition from large computing devices, which took up entire rooms, to the small hand held devices which are used currently (2000s). The Nixie Tubes were a development in number displays. The vacuum tubes contained ten filaments, each in the shape of a different number. The different filaments would be illuminated by different electrical connections. The Nixie Tube displays were later replaced by a seven segment display for numbers.

Condition:

There was general dust and dirt all over the face of the instrument. Yellowing evident all over the off-white plastic portions. Stains and or marks on the top, corner and bottom of the instrument. Crack in lower right corner of the number pad of the instrument, some minor separation. “3″ key has been painted in white and re-drawn. All keys show signs of dirt from use. Dirt stain below the “error” area of the display. Panel directly below the display is discolored. The instrument has not been opened. The condition of the equipment inside cannot be fairly assessed. The instrument does have its cord, however, it has not been plugged in and may not function.

Manufacturer:

Compucorp for Monroe which was division of Litton Industries

Date of Manufacture: ca. 1970

Provenance:

Bought in the 1970s by the geophysics group, no later than 1975. Saved by Nigel Edwards until 2011. Given to Stephen Morris in 2011. Given to the University of Toronto Scientific Instruments Collection in 2014.

Additional Information and References:

Bennington, James Lynne, George Brecher and W.B. Saunders Company. editors. 1984. Saunders dictionary & encyclopedia of laboratory medicine and technology. Philadelphia: Saunders.
Bud, Robert and Deborah Jean Warner. editors. 1998. Instruments of science : an historical encyclopedia. London : The Science Museum ; New York : The National Museum of American History, Smithsonian Institution : in association with Garland Pub.
The Old Calulator Web Museum. 2003. “The History of Compucorp.” Last modified February 7, 2010. http://www.oldcalculatormuseum.com/d-compucorp.html.

Donated to UTSIC: Yes

Historical Notes:

This calculator was purchased and used by the Geophysics department of the University of Toronto. It was used by the department and kept by Nigel Edwards until 2011.