Introduction

Plus & Sumlock Mechanical Calculators
PLUS 509/S Sterling Currency Calculator

Plus model 509/S

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

The calculator in the photograph above displays the total:
£1,234,567 17s 11d.

230 x 190 x 124 mm (9" x 7.5" x 4.9").

This casing style was replaced by a more modern version in 1958.
Made by Bell Punch Co. Ltd. in Britain, distributed by Sumlock Ltd.

The machine illustrated has serial number 509/S/95.899.
With the cover removed.

With the cover removed.
Rear

Rear of the calculator.
Badge

This older style casing has the maker's badge on the back, secured in a recess with adhesive. Often the adhesive weakens and the badge falls off and is missing.

There are excellent photographs and descriptions of the Plus Adder mechanism at John Wolff's Web Museum site. These are accessed from the Comptometers and Key-Driven Calculators section on that site.
Home
Introduction
Origins of Bell Punch Co.
Mechanical Calculator Days
National Calculating Service
Development of Anita 1
Development of Anita 2
Anita is Launched
At work with Anita
All Change at Bell Punch
Anita Developed Further
Anita at its Zenith
The Rockwell Connection
Demise of Anita & Bell Punch
Mechanical Calculators
Early Anita Desktop Calculators
Transistors & Integrated Circuits
Anita LSI Desk Calculators
Anita Hand-held Calculators
Rockwell-Anita Calculators
Calculators made by others
Advertisements & Brochures
Operating Manuals & Materials
Company Information
A Tour of Company Sites
Summary
The Technology Explained
Operating a Comptometer
Old Sterling Currency, £sd
Links
Update Information
Getting in touch

Plus & Sumlock Mechanical Calculators
Plus Adder S
Plus Adder SJ
Plus Adder ST
London Computator 509/S
London Computator 912/S
Plus 506/D
Plus 506/F
Plus 506/T
Plus 509/D
Plus 509/F
Plus 509/S
PLUS 509/SP Weight Calculator
PLUS 509/T Time Calculator
PLUS 509/Y Weight Calculator
Plus 512/S
Sumlock 912/F
Sumlock 912/S
Sumlock 912/Y Weight Calculator
Sumlock 913/S with Certopost
Sumlomatic
Sumlock Comptometer 993m
Sumlock Comptometer 993s

Click here to go to the Vintage Calculators Web Museum

Text & photographs copyright © 2002 - 2008 Nigel Tout, except where noted otherwise.