AIX (is it unix)?

[Guy Harris]

>>I suspect it will be SunOS, based on BSD as always, with
>>more features added.
>
>No, it's not.

Correct, but then saying SunOS 4.x is "based on BSD" is also misleading.
Both SunOS 4.x and S5R4 include code derived from BSD code.  They also
include code derived from V7, from S5R2, from S5R3, and written afresh
for S5R4.

>It might look like BSD if you're running with a BFS (Berkeley
>File System) and the BSD-style tty driver (supplied by a streams
>module)

By "BSD-style tty driver" do you mean the streams module that supplies
"tty driver" functionality ("ldterm"), or one that maps V7-style,
BSD-style, and presumably Xenix-style "ioctl"s into the extended
S5-style "ioctl"s that "ldterm" supports" ("ttcompat", unless they
changed the name from its name in SunOS)?

>but it's really a System V kernel with lots of BSD and SunOS features and
>user-level utilities added.

Well, yeah, since it's System V it is, by definition, a System V kernel.
However:

	the VM subsystem is different from that of earlier S5 releases
	(based on SunOS 4.x, and therefore not particularly like BSD);

	the process management code is different from that of earlier S5
	releases (written for POSIX, etc., and not particularly like BSD
	internally);

	the scheduler is different from that of earlier S5 releases (to
	support selectable scheduling policies - and it's not
	particularly like BSD internally, either);

	the pluggable-file-system mechanism is different from that of
	earlier S5 releases (based on SunOS 4.x VFS, with some grot
	cleaned up - and not like BSD, since current BSD doesn't *have*
	a pluggable-file-system mechanism);

so, while it's not "BSD-based" in the sense that they didn't start with
BSD, enough has changed from previous S5 releases that it's not just a
minor tweak on S5R3, either.