Operating a Comptometer

Plus & Sumlock Mechanical Calculators
PLUS 509/D

PLUS 509

Plus model 509/D/892604

Simple "Comptometer" type adder.

This is a direct action keyboard calculator of the "comptometer" type. It has an abbreviated keyboard (keys up to 5) and is designed for decimal calculations.

235 x 182 x 120 mm (9.25" x 7.2" x 4.75").

Made in or after 1966, when Sumlock Anita Electronics was formed to manufacture the electronic and mechancal calculators.


The label showing that this machine was made by Sumlock Anita Electronics Ltd.

Origins of Bell Punch Co.
All Change at Bell Punch
Development of Anita 1
Development of Anita 2
Anita is Launched
At work with Anita
National Calculating Service
Anita Developed Further
Anita at its Zenith
The Rockwell Connection
Demise of Anita & Bell Punch
Mechanical Calculators
Early Anita Desktop Calculators
Transitors & Integrated Circuits
Anita LSI Desk Calculators
Anita Hand-held Calculators
Rockwell-Anita Calculators
Calculators made by others
The Technology Explained
Operating a Comptometer
Old Sterling Currency, £sd
Update Information

Plus & Sumlock Mechanical Calculators

Petter S
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Plus 509
PLUS 509 Time Calculator
PLUS 509 Weight Calculator
Plus 512
Sumlock 912
Sumlock 912 with Certopost
Sumlock 912 Weight Calculator
Sumlock Comptometer 993m
Sumlock Comptometer 993s

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Text & photographs copyright © 2002, 2003 Nigel Tout, except where noted otherwise.