222 Gallery
222 Downloads
S#74005
S#74005 - Technical Description
This page has downloadable drawings and information for our Soemtron ETR222 electronic calculator serial number 74005. Updates and corrections to the drawings will be uploaded on an ad-hoc basis as it comes 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 ....". All files on this website are ©2007– www.soemtron.org and its group websites[2] or the files respective owner.
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.
September 2017 – Reverse engineering our Soemtron 222 has just started and initial results have confirmed that the 222 is in fact derived from the ETR224, not the ETR220 as we thought some while ago. Several of the main PCB's are labelled "224–" (the "4" is scratched out) and several "22 –", with several being at the same issue level as the corresponding PCB of the ETR224 board.<
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) |
Keyboard assembly - for the ETR222 blue keyboard variant. (43.5Mb) |
Card cage and backplane assembly - (9.6Mb) |
Soemtron ETR222 Circuit and Logic diagrams –
(See the "Snagging list" file for the current list of things to check with our ETR222) | |||
Power supply | circuit | updated | 28/02/2024 |
Keyboard | circuit logic |
updated updated |
16/08/2024 24/03/2021 |
Display | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 1 – Core store, read amplifiers and digit drives 2–4 | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 2 – Core memory drivers and decoding | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 3 – B1–4, VOR and Unknown function latches | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 5 – 5 bit address "Z" counter | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 5 – 25Khz clock, R, F6, undetermined functions, 14 drive signals | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 6 – Wheel position, M latch, undetermined function, various gating | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 7 – B1–4, Arithmetic unit A Register, digit drives 5–9 | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 8 – F1/3, Arithmetic unit E Register, Carry latch and digit drives 0/1 | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 9 – READ/WRITE, S1, V, miscellaneous gating | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 10 – MZ, miscellaneous gating circuit | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 11 – UBER, F2, VER, DOUBLE, and minor gating | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 12 – F1, F3, F4 and F5 | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Board 13 (under keyboard) - Display drivers, MINZ, SPE, keyboard debounce | circuit logic |
updated updated |
24/03/2021 24/03/2021 |
Backplane | circuit | updated | 24/03/2021 |
Block diagram | block | updated | 24/03/2021 |
All current circuits for the Soemtron ETR222 (6.9Mb file) | circuit | updated | 16/08/2024 |
All current logic diagrams for the Soemtron ETR222 (3.2Mb file) | logic | updated | 24/03/2021 |
Current problems with the circuits for the Soemtron ETR222 | snag list | updated | 24/03/2021 |
1 | Download Adobe Acrobat | Adobe reader download.[top] |
2 | Group websites | www.soemtron.org www.soemtron.com www.soemtron.eu www.pdp-7.org www.pdp-7a.org[back] [top] |
3 | IronCAD | Latest IronCAD download.[back] [top] |
4 | IronCAD Compose | IronCAD Compose download.[back] [top] |
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