Contex00.jpg (13330 bytes)
Contex60.jpg (10196 bytes)

"The first attachment is a photo of a sterling-currency version of this model. The actual machine is in a museum display, so I was unable to investigate it closely.

The second attachment is a photo of a functionally identical Contex from my collection, in what looks like 1960s styling. The serial number is 911428. Michel Bardel's list dates Contex production to 1960, so this was presumably  a fairly late model. It still has the price ticket underneath - it cost 24 pounds 15 shillings, roughly equivalent to 50 US dollars.

The Contex mechanism is very simple, with many parts constructed from red fibreboard. It's operation is unusual in that all the keys in a row move together - pressing (say) the 4 key picks up the 3,2,and 1, and then the  whole lot move down together to the bottom of the stroke. The stroke of the topmost keys is a full inch, which must have been very awkward for the operator, and there is no protection against partial depression (as in the Comptometer).

I have partially disassembled this latter machine, and taken a number of photographs of the mechanism. I hope to annotate these and make them available shortly."  John Wolff.

Source: John Wolff - Melbourne, Australia - July 6, 1999

"I looked at the bottom of my Contex and it has three US patents: 2472519, 2499946 and 2503613. The sales of Contex in Sweden began 1946 and that may be the correct introduction year because Denmark and Sweden are near neighbours." Timo

Source: Timo Leipala (THE OFFICE - January, 1950)


Recently I have been able to spend a little time re-organising the Contex machines in the collection and searching the web for supporting information.  Data from your site has been helpful, as has information from Leif  Kristensen.  Although I did not set out to amass Contex machines I do seem to have quite a lot, some thirty in all!   From these I have been able to deduce some perhaps useful information.
I have eight of the so-called "A" models and can identify four different machines in this group.  The brown bakelite models include decimal keyboards, and sterling keyboards with and without farthings.  There is also a white plastic (bakelite?) model with a sterling keyboard.  All of these have apparently sequential serial numbers, the earliest being 73,053 and the last (white machine) 124,773.
I also have eight of the "B" models and can identify three different machines, being decimal keyboard, and sterling with and without farthings.  The serial numbers for the sterling machines seem to follow on from those of the model "A", from133,605 to 605,885.  With the decimal keyboards, all bear serial numbers of nine digits starting with "411", and I deduce this to be a model number, supported by evidence in the next paragraph.
The remaining machines are the adding/calculating models with the 0-9 keypad.
There appear to be two different machines within the "Contex 10"  label.  One type has a dark grey plastic body and the serial number again of nine digits but starting with "431".  The second type is of a lighter grey, has a slightly different register presentation and the serial number  commencing with "434".  A former serviceman on the Contex machines confirms the existence of an upgraded model 10, identifiable by the plastic colour.
The "Contex 20" models I have feature the dark grey plastic case, and serial numbers beginning with "453" .  The same serviceman said that there was an upgraded model with the lighter grey case but I have not been able to locate one of these.
The "Contex 30"  models have the serial numbers beginning with "473",  and the "Contex 55" models with "493". 

X-Number World of Calculators