Thanks for the writeup, luckily i have a complete system with 2x8" floppies.
It is a SE-90, like this :
http://www.thepcmuseum.net/details.php?RECORD_KEY%28museum%29=id&id%28m…
A very early system, and handwritten notes in the docu suggest it was a temperamental
beast.
I do wonder how may wd900 systems are still around.
Likewise for the QBUS variant of the WD9000, that must also be extremely rare.
Jos