The Addo-X 341E is an electrically driven adding machine. The keyboard has a 10-key number pad with function keys arranged symmetrically around it. There are several variants with regards to the paper feeding mechanism, the most common of which is a simple paper roll. The version here has a wide typewriter style carriage for paper sheets, but also has a spool attached for paper rolls.
The machine allows an input of 10-digit numbers, and has an 11-digit register that handles negative values. To the right of the keyboard is a large plus button which will cause the current input to be printed and added to the main register, after which the input is cleared. The large minus button to the left of the keyboard does the same except that it subtracts and prints the number with a minus sign after it.
The two red buttons at the top right are the Sub-Total and Total buttons. These print the current value of the register in red with a square or asterisk symbol after it. If the (sub)total is negative, there is a A printed after it as well, meaning Credit. In the Total was requested, the register is cleared.
The two red buttons at the top left are used in multiplication, or rather, repeated addition. These two buttons act the same as the minus and plus buttons, except that the input is not cleared. Holding the button down with therefore add/subtract the input repeatedly until the button is released. There is a small switch to the left of these buttons, and if the switch is in the upper position then the Step-O-Matic is activated. This will append a zero to the input whenever one of the multiply buttons is released. An experienced operator can use this to speed up multiplications.
There is a Non-Add button located away from the symmetrical keyboard, and pressing this will print and clear the input without affecting the current totals register, wihch is useful for order numbers or dates.
It has serial number 615,026. The paper feeding mechanism is easily removed by taking out four screws. In that respect it has a similarly modular design as the Burroughs Portable.
A short demonstration of the machine.
The Addo-X 351 adding machine is the successor to the model 341 above. It has the exact same functionality, but has a somewhat improved mechanism and an entirely new case. The buttons are the same, with one extra button that opens the top of the case to give access to the ink ribbon.
It has serial number 426,251. The case is extremely easy to remove. Press the button to flip open the top section. Next to each ink ribbon spool is a small clip, and after they have been pushed aside, the whole upper case can be lifted off.
Aktiebolaget Addo was founded in Malmö in 1918 by Hugo Agrell. He had been a salesman, mostly of American and German calculators. When the first world war made the import of these machines more difficult, he had the idea to make Swedish adding machines. His cousin Oscar Prinz was a mechanical engineer, and together they started the Addo company. At first they made machines similar to the Comptator, but then improved on it and added a printing mechanism. From about 1928 they made full keyboard adding listing machines of their own design, and from about 1935 they made machines with 10-key numeric input, named Addo-X.
In 1966 Addo was bought by Facit-Odhner. Facit was slow to merge with Addo, so the two production lines ran simutaneously for a while, essentially competing with each other. This became more problematic when cheap electronics rapidly changed the market for calculators. Addo/Facit was unable to adapt quickly enough, and in 1973 was sold off to Electrolux. Production of the last Addo adding machines ended a year later.
Only models made by Addo will be listed here. Not included are the adding machines made by the daughter company Dixma from 1939 onwards. These were sold under the brand name DIXI and had a Dalton-style keyboard. Also not listed here are the Multo pinwheel calculators.
Addo started out making a relatively simple adder that was similar to the Comptator, an adder based on the Rapid Computer. The first four Addo models were based on this, all using sliders that the user moves with a stylus.
|Addo 1||1918-1920?||9||Like Comptator, metallic.|
|Addo 2||1920-1926||10||On a wooden or later metal base; black finish.|
|Addo 3||1920?-1926||10||As Addo 2, but for British currency.|
|Addo 4||1924-1926||10||As Addo 2, with printing mechanism.|
|Addo 5||1924-1926||10||As Addo 4, but for British currency.|
From about 1927 Addo made full keyboard adding machines, using model numbers starting from 6. Most were available in both manual and electric versions, the latter having an E appended to the model name. The upper case was made from Trolit, a plastic similar to Bakelite, but slightly more brittle.
|Addo 9||9×9||British currency, up to £999,999 19s 11d.|
|Addo 10||9×10||British currency|
|Addo 206||9×9||Like Addo 6 but with extra memory register. Probably first made in about 1940|
|Addo 207||9×10||Like Addo 7 but with extra memory register. Probably first made in about 1940|
|Addo 307||9×10||Like Addo 7 but can handle negative totals. Probably first made in about 1940|
*) Production of these models was greatly reduced when the new 10-key machines were introduced in 1936. Nevertheless they continued to be produced and improved, taking on some characteristics of the later series. The casing was changed to metal, the keys changed from round to square. By the 1940s extra functionality from the later machines was incorporated, and these were given model numbers with 200 (extra register) or 300 (negative totals) added to the base model number. The main reason for the long production of these models is that the full keyboard is more easily adapted for use with British currency and other non-decimal calculations. These later productions mostly took place in Britain.
All later models used a 10-key numerical keyboard and these were named Addo-X, where presumably the X is the Roman numeral for 10. These variants were given base model numbers starting at 20. Again there were also versions with an electric motor which had an E appended to their model name. In around 1940 variants with negative totals functionality were introduced.
|Addo-X 30||9×9||These seem to be simplified versions of the series 20 that have no subtraction.|
|Addo-X 321||10×11||Like Addo-X 21 but can handle negative totals|
In around 1950 the series 40 was introduced. This had a different styling, with a metallic green or grey case instead of black. The keyboard was symmetrically arranged (at least on the electric models), with a large subtraction key on the left of the number keys mirroring the large addition key on the right. There was not just a repeat addition key for multiplication but also a repeat subtraction key. Also new was the Step-O-Matic functionality, which could automatically append a zero when a repeat addition/subtraction key was released, making multiplications faster.
Once again the last digit of the model number indicates the register capacity, and extra functionality was indicated by prefixing one or two digits to the base model number. Most of them are listed in the table below. The various paper feed mechanisms that could be attached were denoted by appending a hyphen and two-digit number to the model.
|Addo-X 40||9×9||These are the base models, which have a register that cannot handle negative totals, and often manual rather than electric|
|Addo-X 241||10×11||This has an extra totaliser register for adding together the totals from the main register. Neither register handles negative totals.|
|Addo-X 341||10×11||The main register can handle negative totals, with an indicator window above the 9-key that shows the sign.|
|Addo-X 441||10×11||This has an independent extra register. Neither register handles negative totals.|
|Addo-X 541||10×11||This has an extra totaliser register for adding together the totals from the main register. Both registers handle negative totals.|
|Addo-X 741||10×11||This has an independent extra register. Both registers handle negative totals.|
|Addo-X 2341||10×11||As 341 but with multiplier keys implementing shortcut multiplication.|
|Addo-X 3341||10×11||As 341 but with multiplier keys, moving decimal point|
|Addo-X 3541||10×11||As 541 but with multiplier keys, moving decimal point|
|Addo-X 4341||10×11||As 341 but with automatic division|
|Addo-X 4541||10×11||As 541 but with automatic division|
There are also versions with larger model numbers, e.g. 5341, 7341, 8341, but these are more bookkeeping machines than mere adding machines. The last one is even a combination of a 341 adding machine with a complete typewriter. Models 47 and 347 are designed for calculating with British currency.
In around 1962 all the machines were redesigned to become the series 50. The light grey plastic case was desiged to be very easy to remove. Functionally this series was very similar to the series 40. The most common models are listed below. All these models were electrically driven, though one manual model was still available which was given the anachronistic model number 331.
|Addo-X 152||8×8||Base electric model, register without negative totals.|
|Addo-X 154||9×10||Base electric model, register with negative totals.|
|Addo-X 351||10×11||Negative totals, step-o-matic,|
|Addo-X 653||12×13||Extra totaliser with negative totals.|
|Addo-X 2353||12×13||Negative totals, multiplier keys|
|Addo-X 3653||12×13||Extra totals register with negative totals, multiplier keys.|
|Addo-X 4653||12×13||Extra totals register with negative totals, multiplier keys, Automatic division|
Models 356 was designed for calculating with British currency.
During this time Addo was also making data processing machines, producing variants of the adding machines as data capture devices, which then stored teh input on punched paper tape or punch cards.
ADDO-X Gebrauchsanweisung (PDF, 3.49 MB or archive.org)
ADDO, Malmö, Sweden
6 page trifold leaflet
149mm × 212mm folded, 444mm × 212mm unfolded
This is the German instruction leaflet for the Addo-X models 40E, 41E and 341E. It has no copyright date, but these models were introduced in 1950, and the code on the last page suggests it was printed in 1957.
Addo-X model 154 (PDF, 7.12 MB or archive.org)
ADDO, Malmö, Sweden
20 page stapled booklet
150mm × 211mm
This is the Dutch instruction manual for the Addo-X model 154. It has no copyright date, but this model was introduced in 1962.
Handleiding voor de Addo-X schrijvende rekenmachines modellen 3653 en 3353. (PDF, 9.18 MB or archive.org)
ADDO, Malmö, Sweden
30 page stapled booklet
150mm × 211mm
This is the Dutch instruction manual for the Addo models 3653 and 3353. It has no copyright date, but this model was in production from 1965 till 1970. The style of the manual, in particular the yellow sidebar with the illustrations, seems to have been influenced by the Facit manuals so presumably this was made after Facit acquired Addo in 1966.
Addo serviceboek 40-serie
Binder with many pages divided in 35 sections
265mm × 316mm × 60mm
This is the Dutch version of the service manual for the series 40 Addo-X machines. The pages are all dated, starting from September 1958. As improvements and other changes were made to the machines, new pages were printed and inserted which were added to or replaced the existing pages to keep the manual up to date.
Spare parts catalogue Addo-X models 353, 351, 355.
15 page softcover book
213mm × 298mm
This is the 1961 spare parts catalogue for models 351, 353, and 355. It shows exploded diagrams of the various sections of the adding machine, with all parts numbers. The book as originally printed was only for model 353, but modified afterwards with additional information about models 351 and 355. A loose supplemental page was inserted for models 152 and 154, which is dated 1962.
Spare parts catalogue Addo-X models 152, 154, 351, 353, 355, and 2353.
32 page softcover book
213mm × 298mm
This is the 1963 spare parts catalogue for models 152, 154, 351, 353, 355, and 2353. It shows exploded diagrams of the various sections of the adding machine on the right hand page, with all corresponding parts numbers on the left hand page. This is the updated version of the 1961 parts catalogue above.
Here are various articles about Addo and its adding machines.
Here are various ads for Addo adding machines and calculators.
Here are some of the patents or the Addo.
|Patent||Filing date||Publish date||Name||Description|
|CH 196,009||16-03-1937||28-02-1938||Aktiebolaget Addo||Repeated addition mechanism|
|DE 913,830||11-01-1952||21-06-1954||Aktiebolaget Addo; Rolf Bertil Andrén||Repeated addition mechanism|
|GB 756,772||09-04-1954||12-09-1956||Aktiebolaget Addo||Adding machine improvements|
|DE 960,771||08-01-1953||28-03-1957||Aktiebolaget Addo; Thure Bernhard Bogert||Printer carriage control
See also: CH 311,851
|DE 1,097,186||21-03-1956||12-01-1961||Aktiebolaget Addo; Gösta Roland Holmström; Ove Gustaf Klingström||Shockabsorber for input mechanism
See also: US 2,985,363
|DE 1,145,394||21-08-1956||14-03-1963||Aktiebolaget Addo; John Lydfors||Printing of multiplier digits
See also: US 3,016,188
|DE 1,196,883||29-11-1955||15-07-1965||Aktiebolaget Addo; John Lydfors||Multiplier keys|
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