Unisonic 790RM-C Handheld Electronic Calculator

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This handheld electronic calculator has a metal and plastic case and an array of twenty-five square plastic keys. In addition to ten digit keys and a decimal point key (in white), it has total, four arithmetic function, exchange, change sign, percentage and clear/clear entry keys (in turquoise). In addition it has a square root key and four memory keys (in orange). A mark behind the keyboard reads: Unisonic 790RM. The on/off switch is to the right of this. Behind the keyboard is an eight-digit green vacuum fluorescent display.
A power jack is on the top edge.
The back of the calculator has a sticker giving calculation examples. It reads in part: 790RM-C. It also reads in part: SERIAL NO. (/) 127212 (/) MADE IN JAPAN. Below this is a compartment for four AA batteries.
The calculator has a black plastic sleeve. Also stored in the sleeve is a pamphlet entitled Unisonic 790RM 8 Digit Pocketable Calculator . . . Instruction Manual. Writing on the last page of the manual indicates that the calculator was purchased August 27, 1976.
Compare 1986.0988.117 (Unisonic 790R-C) and 1986.0988.118 (Unisonic 790RM-C). Similar in general shape of the case are 1986.0988.116 (Unisonic 796-A), 1986.0988.115 (Unisonic 799-A), and 1986.0988.112 (Unisonic 1299R-A).
The calculator.org website indicates that the Unisonic 790RM was both introduced and discontinued in 1978. It also refers to a Unisonic 790RM-1 introduced in 1975. The MyCalcDB website shows a 1978 Unisonic 790RM, taken apart to show a Texas Instruments chip made in Singapore.
Currently not on view
date made
place made
Physical Description
plastic (keys; part of case material)
metal (case; circuitry material)
glass (display material)
paper (manual material)
overall: 1 1/4 in x 3 1/2 in x 6 in; 3.175 cm x 8.89 cm x 15.24 cm
ID Number
accession number
catalog number
Credit Line
Gift of John B. Priser
See more items in
Medicine and Science: Computers
Handheld Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History


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