Around scienceNon-decimal electronic calculators were highly unusual in the days when displays only had 8-digits.
Addometer, operating in Feet and Inches mode, displaying 10 feet, 8 and 15/16 inches.
Addometer Feet and inches calculator
Distinctive features: Feet and inches calculator.
Technical details:
Display is green vacuum fluorescent.
Has Feet and Inches and Metric modes, and memory.
Metric mode has the standard 4-functions, and memory, while Feet and Inches mode does not have multiplication and division, only addition and subtraction.
3.6v (3x AA rechargeable cells).
Integrated circuit - Rockwell A7872-11 (here date coded 1980).
84 x 154 x 42 mm. (3.3" x 6.1" x 1.7").
About 1980.
Addometer Company, Dolton, Illinois, U.S.A.
The [MET] key changes between Metric and Feet and Inches modes.
The [FT] key defines the number just entered as feet, then the [IN] key defines the number just entered as inches, and the [FRA] key the number just entered as a
fraction (rounded to the nearest 1/16th).
In metric mode the calculator operates with a fixed decimal point giving two places of decimals.
This calculator has a case style similar to that of some Rockwell models (see the Rockwell-Anita 201 and 202/SR) and uses a Rockwell integrated circuit. Thus, there appears to be a Rockwell connection in the production of this calculator, however Rockwell had left the calculator market a few years earlier so this connection is unclear.
This calculator was kindly donated by an architectural company and can operate on Feet and Inches for architectural calculations.
Although the Addometer Company, and other manufacturers, had produced mechanical calculators operating in feet and inches for many years, electronic calculators capable of operating in these non-decimal units were late on the scene.
In metric mode displaying 123456.78.
In feet and inches mode displaying 999 feet, 11 and 11/16 inches (which is a few 1/16 ths below the maximum it can display).
On the rear of the case is a fold down stand, typical of the Rockwell calculators using this case style.
Inside the calculator showing the Rockwell integrated circuit.
SCAT THE DIMENSION - FEET and INCH CALCULATOR (FI-21)
Two versions with the same functionality.
Distinctive features: Feet and inches calculator.
Technical details:
Display is 8 digits, red LED.
Has Feet and Inches and Decimal modes.
9v (PP3 battery).
84 x 154 x 42 mm. (3.3" x 6.1" x 1.7").
About 1980.
Manufactured by South Carolina Applied Technology, U.S.A.
This calculator has a very unusual shape with a bulge at the back for the battery compartment, though this allows the calculator to sit at a good viewing angle on a desk.
In feet and inches mode the display makes use of decimal points and a dash. Here it shows 13 feet 7 3/4 inches.
Nowadays there are several models of electronic calculators which operate in feet and inches, and also models which use other non-metric units, such as time (hours, minutes, seconds, and frames, useful for television program technicians).
