In search for vintage books to buy, I found this huge PDF (506 pages in German, several illustrations and photos). About a 1990 Siemens conference. I think during search for TESEUS (a software development system).
One rare computer series called Biin is described there (I think not included in the bitsavers documents). Page 349+
The computers were not successful and are withdrawn. One computer survived, some photos, text in German
Some more interesting hard and software in the PDF. Mainly process computers like SICOMP (comparison table at page 321)
Airport control system DEPCOS with dedicated keyboard (page 340) it’s display layout p 343
Warehouse management system, screenshots p 454
ANSIM Analog computer Simulation (University of Erlangen, Germany) sheets, screenshots p. 472
(I haven’t found any info about that on the web)