Just found this youtube channel devoted to the mysterious machine 
https://www.youtube.com/@MERA400/videos
Nice - a 16 bit mini by the looks of it, word-based, dual-CPU capable, asynchronous but about 400k instructions per second. Memory extensible to 1M word with multiple 64k segments. 7 general purpose registers. 650 units produced.
There’s a wiki here (in Polish) with a gallery here. From there:
Here’s an image from this page with technical detail:
The machine can be fitted with a multiple precision arithmetic unit, capable of fixed and floating point operations.
Edit: oh, and a nice emulator EM400!
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