Before leaving for MS, Cutler worked on an OS codenamed "Mica" which ran on top of an architecture named PRISM (which was a predecessor to the Alpha). The idea

Before leaving for MS, Cutler worked on an OS codenamed "Mica" which ran on top of an architecture named PRISM (which was a predecessor to the Alpha). The idea behind Mica was that it was a microkernel which hosted VMS and Unix personalities on top. It is widely claimed and believed that when he moved with his team to MS that he reimplemented Mica as the NT kernel. http://www.textfiles.com/bitsavers/pdf/dec/prism/mica/ http://www.textfiles.com/bitsavers/pdf/dec/prism/mica/