What was the first "clone" functional Unix (i.e. an OS not derived
from genetic Unix code but highly compatible with genetic Unix)? Idris
is the earliest such OS of which I am aware (at least AFAIK it's not a
genetic Unix), but was it actually the first?
I know of none before this that tried to truly 'clone' all the (v6) kernel functionality and many tools.
Similarly, which was the
first "outer Unix-like" system (i.e. one with strong Unix influence
but significantly incompatible with functional Unix)? Off the top of
my head the earliest such system I can think of is Thoth (which
predates Idris by almost 2 years), but again I'm not sure if it was
actually the first.
Thoth Thucks.... [Kelly Booth gave me one of these tee's years go].
Mike Malcolm did not try to clone UNIX - for one thing, it was in B [which Steve Johnson has spread the gospel of same on his sabbatical). It was not until the Thoth rewrite that became QNX that they tried to ensure all of the Unix behaviors and APIs. Mike was certainly had an influence by UNIX and IIRC his thesis and the Thoth papers reference/compare it.
The first non-C style mostly cone was Holt's Tunis in the early 1980-s (in Euclid IIRC - which is similar to, but different from, Hansen and Wirth's Concurrent-Pascal).