**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.

**Addometer Feet and inches calculator**

**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").

About 1980.

Addometer Company, Dolton, Illinois, U.S.A.

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).

Inside the calculator showing the Rockwell integrated circuit.

**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").

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 & 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 Nigel Tout 2000-2020 except where noted otherwise.