[TUHS] First Unix-like OSes not derived from AT&T code?

[Dan Cross]

On Mon, May 2, 2022, 2:43 AM Phil Budne <phil at ultimate.com> wrote:

> Ron Minnich wrote:
> > in terms of rewrites from manuals, while it was not the first, as I
> > understand it, AIX was an example of "read the manual, write the
> > code."
>
> My memory, from having a "finger" program that tried to display the
> foreground/active process for each tty/login/utmp entry, is that there
> it was possible there were multiple code bases (tho it's possible
> there was just one, and it mutated wildly across major versions), all
> called "AIX" (and as my old boss, Barry Shein (BZS) at Boston
> University said, they all "will remind you of Unix"), there were (at
> least) versions for:
>
> RT PC
> RS/6000 (POWER, PowerPC)
> PS/2
>
> I never had access to AIX/370, but BZS got a chance to try it out in a
> VM on the academic computing S/390, and ISTR he said it finished
> compiles before you hit return.
>
> There was also a (pretty clean, ISTR) port of 4.3 BSD to the RT called
> "ACIS", but it might only have been available to academic sites.
>

The RT 4.3 port was called AOS (for the, "Academic Operating System"). It
was mostly Tahoe with NFS and came with most of the sources, but some bits
were distributed only as object code: I believe some of the MM bits?
Perhaps the MMU code? I vaguely recall this being one of the things people
had a hard time with when trying to port Reno and 4.4 to the RT.

ACIS was, I believe a marketing term for the RT running AOS as sold to
universities.

The port was fairly faithful; the C compiler was a bit strange "High C" or
"Hi C", bit GCC was available after a while, but had some bug and could not
compile the kernel.

Charlie Sauer kindly answered some AOS/RT questions on this list a few
years ago, but as I'm typing this on my phone, I can't look them up right
now. :-(

My memory is also that IBM had a very broad license for SVR2 and when
> the Open Software Foundation came together (with people who weren't
> AT&T or Sun), IBM was able to offer that up as a code base.


My understanding is that AIX on the mainframe was closer to OSF/1 than to
AIX on the RS/6000, which was rather different than AIX on the RT.

RS/6000 was the successor to the RT, and AIX on the latter stopped after
version 2, so I'm guessing RS/6k was more evolved than RT AIX, while (as I
heard it many years ago) mainframe AIX was its own thing; the name was
mostly marketing.

        - Dan C.
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