Hand-held Calculators

Feet & Inches calculators

Non-decimal electronic calculators were highly unusual in the days when displays only had 8-digits.

Below are two feet & inches electronic calculators:

Addometer, operating in Feet and Inches mode, displaying 10 feet, 8 and 15/16 inches.

Distinctive features: Feet and inches calculator.

Technical details:
Display is green vacuum fluorescent.

Has Feet & Inches and Metric modes, and memory.
Metric mode has the standard 4-functions, and memory, while Feet & 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").

The [MET] key changes between Metric and Feet & 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 & Inches for architectural calculations.

Although the Addometer Company, and other manufacturers, had produced mechanical calculators operating in feet & 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 & 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 & INCH CALCULATOR

SCAT THE DIMENSION - FEET & 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 & Inches and Decimal modes.

9v (PP3 battery).

84 x 154 x 42 mm. (3.3" x 6.1" x 1.7").

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 & 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 calcuators which operate in feet & inches, and also models which use other non-metric units, such as time (hours, minutes, seconds, and frames, useful for television program technicians).

Hand-held Calculators

Vintage Calculators

Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.