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Diehl

Diehl EVM 18

The Diehl EVM is an electrically driven mechanical calculator with a stepped drum mechanism, a full keyboard, and which features fully automatic division and semi-automatic multiplication. It was made from 1954 until 1962. It has 18 digits in the register, and 9 digits in the counter and on the keyboard.

Most of the controls are obvious, except for the division buttons.

On this version the register's carry mechanism is in the body of the machine so does not extend to any part of the carriage that sticks out to the left. In about 1956 the carry mechanism was redesigned and put in the carriage itself. Also, the division abort lever was moved next to the division buttons. My machine is therefore a relatively early one.

On the bottom is a plate showing the model and serial number. Its serial number is 26,373. In the hole near the side is a slider that releases any buttons that may have been pressed accidentally when moving the machine about.

The carriage is very easily removed. Pushing the little metal tab on top of the carriage releases a catch which allows you to pull out the rod that the carriage is attached with. When the carriage is removed, you have access to a voltage selection switch, 110 or 220 volts. It has a universal electric motor.

In a normal stepped drum mechanism there is a single sliding gear that engages with each stepped drum. The problem with that is that to select a 9 the gear has to move much further than when selecting a 1. In the Diehl the single sliding gear is replaced by two sliding gears, halving the amount of travel needed. In this way the all the number keys in a column need approximately the same small amount of force to be pressed.

Video

Here is a video where I demonstrate the Diehl EVM.

History

Archimedes calculators had been produced since 1906 in Glashütte, a town in Germany, South of Dresden and close to the border with Czechia. It was a centre for the manufacturing of precision mechanics with many watch and clock manufacturers based there. Near the end of the second world war, the Archimedes factory was completely destroyed. When the war ended it was soon rebuilt, but it was located in the Russian zone. Ulrich Eichner, the son-in-law of the Archimedes founder Reinhold Pöthig, together with Wilhelm Kiel and a few other Archimedes engineers moved to West Germany, taking with them many patents and pending patents. There they developed a new machine, and negotiated with Diehl to put it into production.

Diehl was a metalworks company founded in 1902 by Heinrich Diehl and his wife Margarete in Nuremberg. It started as a small foundry and craft workshop, casting art pieces and other bespoke items, and as it grew they shifted to mass production of door knobs and fittings. In the first world war they made copper parts that other manufacturers would use to make bullet casings. Diehl would then continue to cast and press semi-finished products for other industries, for example supplying parts for the rail industry, and making pipes. In the second world war they again made ammunition, so much of their production line was destroyed, or dismantled immediately after the war.

Diehl had to rebuild its production, and not only went back to making many semi-finished products and precision parts, but also started producing clocks. When Eichler and the other Archimedes engineers came to Diehl with a calculator design it was a large and ambitious project to take on, as the proposed calculator had about 2600 precision parts. However, the Archimedes brand name was valuable and Eichner still had contacts with former Archimedes distributors who would be able to sell such a machine immediately, so this was a reasonable step for Diehl to take. After two years of development, the Diehl model A began production in 1952. By the end of the year the model B appeared, which was a more expensive model that included multiplier keys. Further similar models were developed and sold until about 1965. A 10-key listing calculator called the Diehl Transmatic, first released in 1963, soon became the more popular calculator, and variations of this were developed and sold until 1972.

Diehl tried to switch calculator production towards electronic desk calculators, but this was not so successful. The company was easily able to withstand such a setback because it was large and diverse, still making many semi-finished products, ranging from pipes and alloys to parts for white goods. The company still exists today.

Models

Diehl made several series of stepped drum, full keyboard calculators. The series varied in the amount of extra functionality, and hence in price. Below is a table listing the various models and the functionality that they have. All models were sold in two register sizes, 8×7×15 and 9×9×18.

The functions listed in the table are:

Not listed in the table is automatic rounding functionality, and machines that could do this had A/A appended to their model designation. Also not listed is the EVMH, a special version of the EVM which had a detachable hand crank for use when a blackout occurs. These were especially made for the German armed forces.

In 1963 Diehl began to make a 10-key listing calculator. It was so capable that soon their other calculators were discontinued. In the US these machines were rebranded and sold by SCM (Smith Corona Marchant).

Diehl then began making electronic desk calculators, called the Combitronic and Algotronic. They used a narrow strip of punched paper tape for its internal programming, but they were not so successful as they were already outdated when they were released.

Books

Archimedes Diehl Vom Arithmometer zum druckenden Rechensystem
Harald Schmid
Copyright 2014
Verlag W. Sünkel
208 page softcover book
210mm × 297mm × 9mm

This book details the history and mechanisms of Archimedes and Diehl calculators, with many photographs. Available from the Wehrtechnik Museum.

Advertisements and Articles

Here are some advertisements and articles that I found in online archives of newspapers and magazines.

Patents

Here is the list of later patents from Archimedes, which were probably licensed to Diehl and may have partly contributed to the Diehl machines.

Here are patents specifically for the Diehl calculators.

Links

• Diehl still exists, and its website has a nice page about the history of Diehl.
• Rechnerlexikon has a page about Diehl with links to in depth articles, and separate pages about various models like Model A, Model E, Model EVM, and many others.
• The Arithmeum have almost every Diehl machine in their collection: D 18 DR 15 DSR 18 A/A E 15 EvM 15 EvM 18 EvMH 18 EvMS 15 EvMS 15 A/A EvMS 18 A/A FR 18s KR 18 V-L 18 VSR 18 V 18 Transmatic Transmatic S Transmatic DM Decima Decima demo
• Robert Mařík has a Diehl KR15 in his collection, with video.
• Rechenmaschinen illustrated has a few Diehl machines.
• John Wolff's collection contains a Diehl EVM18s.
• Rechenautomat has a page about Harald Schmid's Archimedes-Diehl Book.

© Copyright 2021 Jaap Scherphuis, mechcalc a t jaapsch d o t net.