In between his work on VMS and VAXELN, and leaving for Microsoft, he was also re...

In between his work on VMS and VAXELN, and leaving for Microsoft, he was also responsible for a system called "Mica" which was intended to be a micro kernel system which supported both a Unix and VMS layer on the system, and was written in an in-house Pascal-like language called Pillar. FWIW, NT was inspired by some of the ideas they had while designing Mica.

http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/prism/m...