1) Full-keyboard key-driven calculators
- Have a column of keys 1-9 for each decade. Not pressing a key in any column leaves 0 there.
- Add immediately a key is pressed.
- Basically only perform addition, though the other functions are possible using special techniques.
- Keys in different columns can be pressed simultaneously.
- A lever on the right clears the accumulator register.
- Abbreviated keyboards are possible with columns of keys 1-5 for each decade.
Examples
2) Full-keyboard "Add-lister" calculators
- Have a column of keys 1-9 for each decade. Not pressing a key in any column leaves 0 there.
- Keys pressed are latched. The number entered is printed on the listing paper and added to or subtracted from the accumulated total by pulling the lever.
- Basically only perform addition and subtraction, though the other functions are possible using special techniques.
- Totals and sub-totals can be printed.
Examples
3) 10-key "Add-lister" calculators
- Have only the one set of the 10 keys 0-9, like a modern calculator.
- The digits of numbers are entered sequentially, as on a modern calculator, and are latched internally. The number entered is printed on the listing paper and added to or subtracted from the accumulated total by pulling the
lever.
- Basically only perform addition and subtraction, though the other functions are possible using special techniques. Advanced calculators may be able to perform multiplication and division automatically.
- Totals and sub-totals can be printed.
Examples
Olivetti Summa Prima (with Sterling currency keyboard)
4) Rotary pin-wheel calculators
- Numbers are entered by moving levers to the required digits (on calculators made by Facit a keyboard is used). This raises the same number of pins on each pin-wheel as the number set in that decade.
- Rotating the mechanism, either manually with a crank or by electric motor, adds the number entered to the accumulator (or subtracts the number from the accumulator if rotated in reverse).
- By rotating multiple times and shifting the accumulator very fast multiplication and division is possible.
Examples
5) Stepped gear calculators
- Have a column of keys 1-9 for each decade. Not pressing a key in any column leaves 0 there.
- Pressing a key shifts its associated stepped gear sideways so that the number of teeth engaged is the same as the number on the key.
- Rotating the mechanism, either manually with a crank or by electric motor, adds the number entered to the accumulator (or subtracts the number from the accumulator if rotated in reverse).
- By rotating multiple times and shifting the accumulator, very fast multiplication and division is possible.
Examples
Madas (driven by electric motor)
6) "Troncet" type stylus calculators
- Small, flat calculators, with vertical windows behind which sliding strips with holes and the numbers 1-9 can be seen.
- Numbers are entered by inserting the stylus in the hole against the required digit and sliding the strip to the end of its movement.
- Any carry must be performed manually.
- Usually have one scale for addition and one for subtraction.
- Basically just perform addtion and subtraction.
Examples
Addiator (sterling currency version)
Bowler Countess (Sterling currency version)
Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.