Sadly Peter Neumann has passed away

[erronis]

1. A giant. I never met him but worked with Multics in the late 1960s/70s.

That OS (Multics) was really the progenitor of most of today's multi-user systems. Multics was far ahead of the field in terms of security and general design principles. Unfortunately it had very stringent hardware requirements (multiple security rings, advanced memory management techniques) that made it hard to implement in the available hardware of those days. Our General Electric commercial operating systems (GECOS) were all designed and documented using Multics - sadly not using most of the advanced features.