Anyone heard of the S1 Operating System

[wrcooke at wrcooke.net]

Reading through the April 85 issue of Byte, I came across a reference to the "S1 Operating System."  In Jerry Pournelle's column on pg 361 he talks about this mysterious OS.  Here is a small excerpt:
Robert Knight. formerly of
Princeton's computer laboratories. is
an old fan of my books and columns
as well as the creator of SI. which he
had running on an IBM Instruments
CS9000 

Anyway, my Googling turned up nothing on the OS, although I did find a Robert Knight at Princeton, but no information on stuff he's done.  I will likely email him to ask about it, but wanted to ask here first if anyone knows anything about it.

Thanks,
Will