I'm pretty sure it  was in TS also, but I'm willing to bet it was PWB1 first.  Have to ask someone like Mashey.

FWIW: The issue on time for BSD was somewhat forced by the ARPA community.  The 60th (or 50th) of second (much less 1 second) started to not be fine enough for many applications.   I remember a big argument at a system seminar circa 82/83 about it.   IIRC it was Mike Powell (DEMOS fame) that was bitching at Joy about it.  In the end, BSD4.2 ended up with new time calls because of that community and started doing things in 100th of second - which again IIRC was the best the Vax could do.

I've forgotten what the time resolution on the PDP-10s were, but the Crays and CDC boxes of the day, were much more fine grained than the Vaxen.    Joy was trying to bring Unix closer to what the labs wanted, since they were paying a lot of the bills.   

On Tue, Mar 6, 2018 at 1:11 PM, Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:
    > From: Dave Horsfall

    > When did sleep(2) become sleep(3)?  Was it V7, or some BSD?

Before V7. The MIT system (~PWB1) says, on the man page for sleep (II), "As of
this writing the system call is still available although the C routine
implmeneting the function uses 'alarm' and 'pause' (II). It will be withdrawn
when convenient."

Probably left the system call there for compiled commands, etc which used it?