Compucorp 320G

Plus & Sumlock Mechanical Calculators
Petter S
Petter S

Petter S

Sterling currency, key-driven ("Comptometer") type, with abbreviated keyboard (only has keys 1 to 5).

The photograph above shows a total of £123,456 17s 11d.

230 x 153 x 105 mm.. (9" x 6" x 4.1").

1930s.

Made in England.

This calculator has no manufacturer's name. However it does have lists of patents, and the three U.S. ones were taken out by Guy Bazeley Petter, with rights assigned to Petters, Limited, Yeovil, England (the internal combustion engine manufacturer). One of the patents had been applied for in Great Britain in 1923 and the other two in 1930.
This is almost certainly a Petters calculator, and was the precursor to the Bell Punch "Plus" models.

The case is unusual in being made of Bakelite.
Cover removed

With cover removed, showing the mechanism.
Rear

On the rear of the case is a recess which appears to be where a maker's badge was held in place with adhesive.
This is similar to the recess for holding the badge of the early "Plus" calculators, see the Plus 509/S.
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Introduction
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
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Anita Developed Further
Anita at its Zenith
The Rockwell Connection
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Mechanical Calculators
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Anita LSI Desk Calculators
Anita Hand-held Calculators
Rockwell-Anita Calculators
Calculators made by others
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Operating Manuals & Leaflets
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Summary
The Technology Explained
Operating a Comptometer
Old Sterling Currency, £sd
Update Information
Getting in touch

Plus & Sumlock Mechanical Calculators
Petter S
London Computator 509/S
Plus 506/D
Plus 506/F
Plus 509/D
Plus 509/S
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

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