The German "Rheinmetall" heavy engineering works was established by Heinrich Ehrhardt in Düsseldorf in 1889 as the "Rheinische Metallwaren und Maschinenfabrik Aktiengesellschaft" (Rhein Metalwares and Engine Works Corporation) and registered on May 7th 1889. In the same year production started in rented accommodation in Dusseldorf's Talstrasse, and almost within a year they are employing 1,400 people producing 800,000 bullets a day. In 1901 a munitions factory was then acquired in Sömmerda, a small town near Erfurt in Thuringia, Germany, on the Unstrut river. Following the first world war the Sömmerda factory started producing office machines, typewriters, mechanical calculators, adding and listing machines, they continued to further develop their range of machines upto the second world war in 1939-45.
Following the second world war, the Sömmerda factory then found itself in the newly formed East Germany, with development and production now continuing as a state-run enterprise, but using the pre-war Rheinmetall name and logo. In 1957, a group of young electronics engineers under the collective direction of Heinz Skolaude brought V.E.B.  Büromaschinenwerk  Sömmerda into the age of electronics. In 1960 the name was changed to "Supermetall" and then later to "Soemtron" in 1962, when they exhibited at the Leipzig Fair of that year an electronic Fakturierautomaten  - the model EFA 380. 1963 saw the next model the EFA 381 with magnetic core memory.
When the new brand name "Soemtron", composed from the words "SOEM"merda and Elek"TRON"ik, appeared, the long running legal dispute with the Düsseldorf Rheinmetall Group to the trademark "Rheinmetall" was resolved, along with use of the company logo and patent rights. Previously to this, machines were sold under the trade name Supermetall. In 1966 V.E.B. Büromaschinenwerk Sömmerda then released the first of three electronic calculators. These models, with germanium transistors and Ferritkernspeichern , were produced in several versions - the ETR 220, the ETR 222 (which entered production in 1968), and the ETR 224. From 1968 onwards electronic invoicing and accounting systems were introduced including the EAA 382 and EAA 385 systems, and in 1971 the production of printers began. Production of mechanical calculators ceased at the factory in 1967 with the firm moving over to full production of electronic calculators, mainframe and personal computers like the 8-bit computer model 1715 and latterly the Soemtron 286 and 486 PC's right up until they finally ceased all production in December 1991 having failed for many years to keep up with the western world's dramatic advancements in electronics and computing.
With around one million computers, calculators and office machines, V.E.B. Büromaschinenwerk Sömmerda was probably the largest manufacturer of mechanical and electronic computing technology in the eastern Bloc. Much of the information summarized here originates from a book by Annegret Schule, "BWS Sömmerda" (Desotron Erfurt 1995 ISBN 39-8039-311-9), which describes the history of the enterprise in some detail. Further information and numerous photos of the different Rheinmetall-Soemtron models can be found in a book by Alfred Waize, "Die Welt der Rechenmaschinen" - "The world of the Calculating Machines" (Desotron Erfurt 1999 ISBN 39-3287-509-5).
Manufactured from 1966 to 1977 by V.E.B. Büromaschinenwerk Sömmerda, the Soemtron ETR series of calculators are by modern standards very basic six and seven function calculators with a 15 digit Nixie tube display or mechanical print mechanism. Three different units (and possibly four) were produced in the eleven year production run of these increasingly rare early electronic calculators from the Eastern Bloc.
Rumors continue to surface about the existence of a fourth ETR type, the extremely rear ETR 221, another printing variant like the 224 but split into two housings with a long umbilical cable. One machine apparently existed in London at the offices of the UK importers "Office and Electronic Machines". Further information about the 221 can be found on the 221 page from the menu links above.
The Soemtron series of calculators were imported into the U.K. from the D.D.R. by a company called "Office and Electronic Machines", who were based in London, but with the advent of small calculators using logic chips or basic processors during the eleven year production run of the Soemtrons, their sales market and use was mainly restricted to Eastern Bloc countries.
In 1959 and 1960 Walter Kasper of VEB Elektronische Rechenmaschinen Wissenschaftlicher Industriebetrieb Karl-Marx-Stadt, as the inventor, applied for patents in Germany, France, England and Holland for a "Calculating Device" for the serial addition or subtraction of two binary numbers with BCD correction. The patents are - (with date filed / date granted) -
The Soemtron 220 range also appeared in the "Büromaschinen Lexikon", a German technical publication covering office machinery and related products. Soemtron branded products appeared in all the issues between 1962 and 1969 but only three entries are available online below -
If you have any further historical information, circuits, drawings, photographs, data or manuals about the Soemtron ETR 220, 221, 222, 224 or their manufacture, test equipment (Prüfgeräte) or you just know more about the Soemtron companies in general then please let us know, contact us here.
Some of the information on this page has been derived from www.robotrontechnik.de with grateful thanks.