"the OS that introduced this innovation" -- I don't like that
phrase, it offends my pride as a long-time TOPS10 programmer. TOPS10
is, I think, the OS that introduced the innovative device "pty". BSD
merely incorporated the concept into Unix (and didn't do a very
satisfactory job of it).
So, what historical perspective does TOPS10's implementation
of PTYs have to offer on the issue at hand? Gee, I was afraid you'd
ask that. :-/ TOPS10 didn't have a "fork" operation; essentially, the
PTY master had to be opened before the slave's subprocess could even
exist.
Craig Milo Rogers