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Addo

Addo Model 2

The Addo Model 2 is an adding machine somewhat reminiscent of the Rapid Computer or Comptator. The machine has 9 sliding rods, which allow you to enter any number of up to 9 digits. Further forward is a window with a 9-digit register. The front plate is painted black, and has the text "Aktiebolaget Addo, Malmö, Patent, Mod. 2" in gold letters. It is mounted on a wedge-shaped wooden base that has a compartment for a stylus.

Each sliding rod has notches marked 1 to 9. For each digit of the number you want to enter, you put the stylus in the notch of the correct value, and slide it downwards as far as possible. When all the digits have been entered, the number can be read back in the lowest row of notches. Each rod has a little knob at the top allowing you to make corrections by pulling it back up.

To add the entered number to the register, pull the lever on the right towards you and then allow it to return to its original position. This action resets the input rods, and finalizes the addition by performing any carry operations that were necessary (the digit values were already added when the number was entered).

The smaller lever resets the register to zero. Unfortunately this lever can only be used while the addition lever is also pulled forward. This makes the machine rather awkward to use.

It has serial number 2041, which is stamped into the far side. This is the lowest serial number that I have found anywhere online, so it was probably made in 1920 or 1921, the start of its production run. The numbering may have started at 2000. Later machines have a register with some sets of red number wheels to mark off the groups of three digits. Still later machines are mounted on a metal base instead of a wooden one.
Most adding machines of a similar type perform carries simultaneously, which can make it hard to enter a number when multiple carries occur. In the Addo 2 the carries are performed ripple fashion, triggered by a rotating drum with a helical arrangement of pins.

The rubber feet have deteriorated, becoming squashed, hard and brittle, but they remain fairly intact. The rubber spacers between the base and the machine were mostly broken so I have replaced them.

Video

Addo-X 341E

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.

Video

A short demonstration of the machine.

Addo-X 351

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.

History

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 Printz 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 1927 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.

Models

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 adders 1918-1926

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.

Below is a list of the serial numbers for models 2-4 that I have found online, with descriptions.

Addo machines, 1926-1936/1958*

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.

*) 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.

Addo-X series 20, 1936-1950

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 series 40, 1950-1962

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.

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.

Addo-X series 50, 1962-1974

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.

Model 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 the input on punched paper tape or punch cards.

Manuals

Wie Man Rechnet Gebrauchsanweisung fur die ADDO-X Serie 40     (PDF, 8.35 MB or archive.org)
ADDO, Malmö, Schweden
1955
15 page stapled booklet
147mm × 209mm

This is the German manual for the Addo-X models series 40. The back page lists all the models 40E, 41E, 42E, 345E, 341E, 40, 41, 42, 341, and 241E. It briefly describes addition, subtraction, negative totals, multiplication, with calculation exercises.

ADDO-X Gebrauchsanweisung     (PDF, 3.49 MB or archive.org)
ADDO, Malmö, Sweden
1957?
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
1962?
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
1965-1970?
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
A.B. Addo
1958-1962
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.
A.B. Addo
1961-1962
SA 104
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.
A.B. Addo
1963
SA 164
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.

Promotional material

Addo-X, die Addiermaschine unserer Zeit
A.B. Addo, Schuster & Walther
1950?
One-sided flyer
202mm × 294mm

This German advertising flyer describes the Addo-X Series 40. At the bottom the address of a Walther & Schuster branch in Nürnberg has been added.

Articles

Here are various articles about Addo and its adding machines.

Advertisements

Here are various ads for Addo adding machines and calculators.

Addo 1919-1936

Addo-X series 20: 1936-1950

Addo-X series 40: 1950-1964

Addo-X series 50: 1965-1973

Patents

Here are some of the patents or the Addo.

Links

• Rechner Lexicon has a page about the Addo company as well as separate pages for various models including Addo 2, Addo-X 341, and Addo-X 351.
• Rechenmaschinen-Illustrated has pictures of various early Addo adding machines.
• Rechnen Ohne Strom has a page with toothed rack machines, including a the early Addo models.
• John Wolff has page with Addo adding machines.
• Christofer Noering's Swedish Typewriter Page has good info on Addo with photos of the factory.
• Örkeljunga Kommun Fotosamlingen has several historical photos of the Addo factory.
• Vintage Calculators shows some full keyboard machines full keyboard machines and later electronic calculators.

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