Plus & Sumlock Mechanical Calculators
Sumlock Comptometer 993s

Sumlock Comptometer 993s

Sumlock Comptometer 993s (storage)

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 1963.

Price in 1963 £265 Sterling [about US$750 at 1963 exchange rate], in 1969 £280 Sterling [about US$700 at 1969 exchange rate].

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

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.

Electrically safety label

I have been informed of comptometers that have still been used into the 21st century 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 totalling lists.

Comptometer 993S advertisement

Advertisement for the Comptometer 993S, British Sterling currency version, from May 1969.

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

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Text & photographs copyright © 2002 - 2023 Nigel Tout, except where noted otherwise.