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Sumlock Comptometer 993s

Sumlock Comptometer 993s

Sumlock Comptometer 993s

10-decade, decimal Comptometer, electrically driven, with storage (memory).

Model number 912/VZ/S/914.896.

346 x 324 mm x 200 mm (13.5" x 12.75" x 8").

Introduced in 1964.

Made in Great Britain by Bell Punch Company Ltd.
Bell Punch acquired the right to use the name "Comptometer" from the U.S. Comptometer Corporation in 1960.

This machine has the standard full keyboard with 12 decades of keys (1 to 9). As usual on Comptometers, pressing a key adds that number to the accumulator register, as shown in the lower row of windows, here showing 12300000.
Pressing the + side of the rocker switch on the right adds the contents of the accumulator register to the storage register (memory) along the top, here showing 24600000. Pressing the "-" side of the rocker switch subtracts the accumulator contents from the storage register.
The clearing switch at lower right can individually clear the accumulator or the storage registers.

Inside Sumlock Comptometer 993s
Inside Sumlock Comptometer 993s

With the cover removed.

For information about the Bell Punch company and its calculators see the article on this site "Anita: the world's first electronic desktop calculator - A brief history of the complex Bell Punch company and its calculators".

For a detailed history of the development of the Bell Punch and Anita calculators go to the associated site "Bell Punch Company and the Anita Calculators".


The 993 series were among the last new calculators of the "Comptometer" type to be designed anywhere.

When obtained for the collection there was a safety sticker on the side of this machine (see below) showing that the machine had been recently electrically tested and the next test, in a year or two, was due in 1997.
I have been informed of comptometers that have still been used by people who have been correctly trained to use one quickly and efficiently, since they could operate it faster than a 10-key electronic calculator for totaling lists.

Electrically safety label

Click here for more information about Compometers.

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2017  except where noted otherwise.