[huxley]

The NeXT and Rhapsody kernels used NetBSD as the basis for their BSD subsystem, OS X used FreeBSD as the basis for its BSD subsystem.

You are technically correct that it isn't FreeBSD but, for most intents and purposes, Mac OS X re-uses many parts of FreeBSD.

[snogglethorpe]

> The NeXT and Rhapsody kernels used NetBSD as the basis for their BSD subsystem

NeXT started in the mid-80s (I first used a NeXT cube in 1988), and ceased to exist in 1996. NetBSD didn't exist until 1993...

[My impression is that NeXT for a long time used the same "non-server" version of Mach that was generally used at CMU at the time (BSD code originally derived from 4.3BSD still in the actual kernel, not as a separate subsystem).]

[vvhn]

>My impression is that NeXT for a long time used the same "non-server" version of Mach that was generally used at CMU at the time (BSD code originally derived from 4.3BSD still in the actual kernel, not as a separate subsystem).

Right, NeXtStep was derived from Mach 2.5 which had a 4.3BSD emulation layer (still running in the kernel though) on a Mach "not yet a microkernel" (Mach transitioned to a full Microkernel in Mach 3.0 when the BSD emulation moved out from kernel to userspace). When it became OS X, the BSD emulation layer was updated to 4.4BSD (from FreeBSD) and the Mach part was updated to Mach 3.0. As an aside, Apple even experimented with a Linux Emulation Layer on top of a real Mach Microkernel (mklinux http://en.wikipedia.org/wiki/MkLinux) and as the work done in bringing this up actually was put into getting Mach upto 3.0 on xnu (along with the BSD update).

The other Unix which derived from Mach 2.5 was OSF/1->Digital UNIX->Tru64 UNIX.

[freeosjunkie]

Thank you. +1, would read again. I have no mod points.