Nixdorf 620 image on the HNF Blog: EVELYN BEREZIN AND THE WORD PROCESSOR

https://blog.hnf.de/evelyn-berezin-und-die-textverarbeitung/

"From 1974 Nixdorf Computer AG also had word processing in its program. The Nixdorf 620 was based on a system from the US company Entrex." (Translated from German by Google)

Heinz Nixdorf MuseumsForum in Paderborn, Germany.  This looks exactly like their display, with all of the actual background "blacked out"...

https://www.sparkassenmuseum-hef.de/index.php/Detail/Object/Show/object_id/743