Soemtron ETR220 Downloads

S#105669 - Downloads

Soemtron logo of unknown origin

This page has downloadable drawings and information for our Soemtron ETR220 electronic calculator serial number 105669. Updates and corrections to the drawings are uploaded on an ad-hoc basis as various corrections come to hand, but we do not accept responsibility for their subsequent use. The files will usually be in pdf format so a current copy of an Adobe Acrobat[1] reader will be needed. To download the files right click the relevant link and select "file save as ....", or to view the files directly just click the link, assuming you have the pdf viewer installed!
All files on this website are ©2007– www.soemtron.org and its group websites[2] or the files respective owner.

Soemtron logo

If you have any further historical information, circuits, drawings, photographs, data or manuals about the Soemtron ETR220, 221, 222 and 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.

Part number list - a list of all Soemtron part numbers currently available to us from various documents (35Kb)

3D CAD -
Multiple 3D CAD models of various Soemtron parts have been created using the latest version of IronCAD 3D and they can be edited with a free 30 day trial[3], or viewed with a copy of IronCAD Compose[4]. The files are supplied in IronCAD native (.ics) and Step (AP214) formats within a zipped file.

Daro 11 pin connectors - models for the Daro 11 pin plug and socket connectors. (1.9Mb)

Daro 20 pin connectors - models for the Daro 20 pin plug and socket connectors. (2.5Mb)

Daro 32 pin connectors - models for the Daro 32 pin plug and socket connectors. (2.8Mb)

Test connector shorting link - V7 test connector shorting link for normal operation. (184Kb)

Soemtron ETR220 Circuit and Logic diagrams –

(See the "Snagging list" file for the current list of things to check with our ETR220)
Power supply	circuit	updated	30/01/2024
Keyboard	circuit	updated	13/12/2018
Display	circuit	updated	13/12/2018
Board 1 – Core store, read amplifiers and digit drives 2–4	circuit logic	updated updated	12/12/2012 12/12/2012
Board 2 – Core memory drivers and decoding	circuit logic	updated updated	28/10/2014 6/04/2011
Board 3 – Arithmetic unit A Register and digit drives 5–9	circuit logic	updated updated	5/05/2012 5/05/2012
Board 5 – Arithmetic unit E Register, Carry latch and digit drives 0/1	circuit logic	updated updated	11/05/2012 4/04/2011
Board 5 – V, SCHREIB, S1 function latches and 25Khz clock	circuit logic	updated updated	5/05/2012 6/04/2011
Board 6 – Control gating	circuit logic	updated updated	11/05/2012 6/04/2011
Board 7 – B1–4, VOR and R function latches	circuit logic	updated updated	5/05/2012 5/05/2012
Board 8 – F1/3, VER and MZ function latches	circuit logic	updated updated	11/05/2012 6/04/2011
Board 9 – Function F2, F5 & F6 latches, including register addressing	circuit logic	updated updated	11/05/2012 6/04/2011
Board 10 – 5 bit address "Z" counter circuit	circuit logic	updated updated	15/05/2012 6/04/2011
Board 11 – Display Anode drivers and function key encoding	circuit logic	updated updated	24/03/2021 5/05/2012
Board 12 – Display cathode drivers and numeric key encoding	circuit logic	updated updated	05/06/2013 5/05/2012
Backplane	circuit	updated	13/12/2018
Overall block diagram	block	updated	6-04/2011


All current circuits for the Soemtron ETR220 (7.3Mb file)	circuit	updated	30/01/2024
All current logic diagrams for the Soemtron ETR220 (1.7Mb file)	logic	updated	12/12/2012
Current problems with the circuits for the Soemtron ETR220	snag list	updated	13/04/2011

1	Download Adobe Acrobat	Adobe reader.[top]
2	Group websites	www.soemtron.org www.soemtron.com www.soemtron.eu www.soemtron.uk www.pdp-7.org www.pdp-7a.org[back] [top]
3	IronCAD	Latest IronCAD 30 day trial.[back] [top]
4	IronCAD Compose	IronCAD Compose download.[back] [top]