APF Mark 50 Handheld Electronic Calculator

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This handheld electronic calculator is designed for scientific work. It has an array of digit keys with a decimal point key, keys for the four arithmetic functions, a clear entry/clear key, and an equals/constant key. Pushing down a function key allow one to use the digit keys to find trigonometric and inverse trigonometric functions in either degrees or radians. Other keys are converted by the function key to give square roots, natural logs, exponents, pi, and the inverse of a number. Still others perform vaious memory functions. A convert key transforms results from scientific notation to floating point notation or vice versa.
Text on the keyboard reads: aPF MARK 50 SCIENTIFIC CALCULATOR (/) LOG X = LN X + 2.30259.
A hole for the adapter is at the back, as well as a compartment for a battery. The calculator presently has no battery. The lid of the compartment is on the back. A mark on the inside of it reads: JAPAN (/) 0101641. A sticker attached to the back reads in part: aPF MARK 50 (/) OPERATING INSTRUCTIONS. It also reads in part: Use only Model 710 of 751S adaptor (optional) (/) to operate on A.C. (/) Model No. MARK-50 Serial No. J-44134 (/) MADE IN U.S.A. The back has four rubber feet.
The vacuum fluorescent display is behind the keyboard. It has two digits for the exponent, five for the mantissa, and two for the sign (one each for the exponent and the mantissa).
The APF Mark 50 calculator was advertised in the Los Angeles Times on June 8, 1975, as "New!" and "Ultra advanced!" It then sold for $59.95. According to a June 11, 1975, advertisement in the New York Times, the APF Mark 50 had originally sold for $89.95 and was then on sale for $40.00. An October 22, 1975, sale advertisement lists a price of $35. Similarly, a January 4, 1976, advertisement in the Chicago Tribune gives a price of $34.99. A September 16, 1979, advertisement in the Washington Post lists the model as selling for $9.99.
Los Angeles Times, June 8, 1975, p. T19.
New York Times, June 11, 1975, p. 6.
New York Times, October 22, 1975, p. 14.
Chicago Tribune, January 4, 1976, p. 12.
Washington Post, September 16, 1979, p. K5.
Currently not on view
date made
ca 1975
APF Electronics
Physical Description
plastic (overall material)
paper (sticker material)
metal (circuitry material)
rubber (feet material)
overall: 1 in x 3 1/8 in x 5 3/4 in; 2.54 cm x 7.9375 cm x 14.605 cm
ID Number
catalog number
accession 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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