- Soemtron ETR Series Electronic Calculators

Soemtron ETR 220, click image for a larger version, ©2007 Serge Devidts
Soemtron ETR 220
Soemtron ETR 222, ©2007 Serge Devidts
Soemtron ETR 222
Above ©2007 Serge Devidts
(Click an image for a larger version)
Currently only four Soemtron 224's are known in the wild, click image for a larger version, ©2009 Ruediger Kurth
Soemtron ETR 224
©2009 Ruediger Kurth

Manufactured by V.E.B.[1] Büromaschinenwerk[2] Sömmerda, the Soemtron branded range of ETR22x[3] calculators encompassed three variants, the ETR220, ETR222 and ETR224 a calculator with printout.  A possible fourth calculator, the 221, was seen in various sales literature of the period and does show and describe the type 221 printing calculator, but it is believed now to have only existed as a single machine for a publicity release (December 2009) in the Büromaschinen Lexikon[4], a German publication of the 1960's.  That one machine was possibly the one delivered to Office and Electronic Machines (OEM) in London, the UK importers.

This website is dedicated to the Soemtron electronic calculator range and came into existence when an old piece of equipment was received in 2007 from Prague in the Czech Republic, after a Google search for "core memory" during some idle research into the PDP-7 range of computers manufactured by the now defunct Digital Equipment Corporation.  The unit duly arrived, but it was found to be in a very poor state, dirty, rusty and missing its power supply and top covers (photos).  After a few days research and translating some German text off of the baseplate, we worked out what this old dirty corroded hulk was - a Soemtron ETR 220 calculator, which turns out to be a very interesting piece of early electronic calculator history from 1960's and 70's German Democratic Republic.

Over time we have repaired and conserved our Soemtron 220 and eventually we hope to get this interesting piece of Eastern Bloc calculator history from the 1960's into full working order, once we can get a suitable power supply into her.  Bookmark this page and come back from time to time for a visit and see how we are getting on.  We have published and are updating full circuit diagrams (ein schaltplan) of the machine and its inner workings for those of you who are interested - not many probably !, but there again this is the Internet, see you again soon.

The top two pictures (right) are of a very good condition Soemtron ETR 220 and an ETR 222 owned by calculator collector Serge Devidts, for more information see his website.  The bottom picture is of an ETR 224 printing calculator, a very rare machine as just over 500 units were built.

Timeline -
Older news from Soemtron.

August 2014 - There has been a dearth of news for the Soemtron website for some time now as other things in life needed a little attention.  So to catch up -
Our main line of progress has been on the 224 and to update the website to current HTML5 spec where possible.

We have essentially completed the mechanical re-building of the 224 printer mechanisim to the extent that it works reasonably well when manually triggered, but some re-alignment is needed to the print wheels and their rest position.  Work in the last six months has concentrated on decoding the circuitry of the twelve electronics boards in the card cage, to the extent that we now have a full, but unchecked circuit for the 224.  Currently we are working to resolve the temporary signal names (TMP-xxx) that were used in the circuit tracing and to find solutions for the problems in the 224 snagging list.  For further details see the ETR 224 page.

August 2011 - An email from another of our contributors Rocco Thiel has turned up two Soemtron brochures from the 1960's, one for the ETR 220 and one for the ETR 221.  The ETR 221 brochure is especially welcome as we thought that publicity information about this machine did not exist.  Each brochure can be found on their respective machine pages, or here 220, and here 221.

Fourth Soemtron 224 found, click image for a larger version
©2011 Ruediger Kurth
(Click image for a larger version)

May 2011 - Another 224 found.  In an email to Bernard Green, Rüdiger Kurth another of our contributors, has written to say that he has found another Soemtron 224 machine as part of an exhibition in the Museum für historische Bürotechnik Naunhof (Museum of Historical Office Technology in Naunhof) - website.  The machine was apparently made in 1969 and is serial number 32549.  Close examination of Rüdiger's photo shows it is the same build version machine as we have in our collection, which is serial numbered 32612 and also from 1969, this brings the number of Soemtron 224 machines currently known to exist to four.

Previous events in the Soemtron website timeline.

The Soemtron 220 range also appeared in the "Büromaschinen Lexikon", a German publication covering office machinery and products.  Soemtron branded products appeared in the 1962/63 to 1968/69 issues, but only three are available online below -

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1 Wikipedia entry for V.E.B. = Volks Eigener Betrieb, or Peoples Owned Company V.E.B. [back] [top]
2 Büromaschinenwerk Office Machine Works [back] [top]
3 ETR Elektronischer
Tischrechner [back] [top]
4 The index page for the Büromaschinen Lexicon
4a A Soemtron 220, and a 221 with integral printer 1966-67 (then click the  "Soemtron" link)
4b A Soemtron 220, and a version with printer 1967-68 (then click the  "Soemtron" link)
4c Description for the Soemtron 220 and a "fast printer", click the "Sumlock" link to see photos and pricing for the 220 and 224. 1968-69 (then click "Soemtron" & "Sumlock" links) [back] [top]

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