[TUHS] Is there a good, even definitive, list of reimplementations of the Unix kernel? What would good cut-off criteria be?

[Charles H Sauer (he/him) via TUHS]

Clem,

I assumed before saying anything that you would better know/know more 
about the earlier Locus work than I did. I doubt that I was aware of 
Locus until the 1983 SOSP paper, maybe not until later. I didn't really 
know Bruce and Gerry until spending a few days with them in Santa Monica 
in 1987. (Those meetings were coincident with the Whittier earthquake, 
so we all joked that the Austin AIX people coming to LCC caused the 
tremors...)

Regarding all of the object format discussions, particularly "universal" 
binaries, Locus must have had a universal format so that they could 
build a binary that would run on both 386 and 370 (and probably VAX and 
other machines).

Charlie

On 4/19/2026 1:39 PM, Clem Cole wrote:
> A small PS.  I believe there were running into address space issues in 
> the original work, so it probable that be time Bruce started work on his 
> File System (his PhD work) they had Vaxen and would have upgraded to an 
> early vax BSD ie 3 or later.
> 
> 
> Sent from a handheld expect more typos than usual
> 
> 
> On Sun, Apr 19, 2026 at 9:46 AM Clem Cole <clemc at ccc.com 
> <mailto:clemc at ccc.com>> wrote:
> 
>     Charlie,
> 
>     I’ll make a small WAG having been part of the later history. I
>     believe the UCLA ( original ) SOSP Locus paper was based on
>     PDP-11/70s and predated BSD3 [which was the original Vax release]. 
>     It is likely that UCLA had the original BSD for 6th edition and
>     possibly 2BSD which was for both V6 and V7.
> 
>     When LCC was created was post 4BSD and the IBM AIX 370 and PS/2 work
>     for what become TCF  was based on 4.1. I suspect Bruce’s comment was
>     based on the later work.
> 
>     Clem
> 
> 
>     Sent from a handheld expect more typos than usual
> 
> 
>     On Sat, Apr 18, 2026 at 11:49 PM Charles H. Sauer via TUHS
>     <tuhs at tuhs.org <mailto:tuhs at tuhs.org>> wrote:
> 
> 
>          > On Apr 18, 2026, at 9:52 PM, Bakul Shah via TUHS
>         <tuhs at tuhs.org <mailto:tuhs at tuhs.org>> wrote:
>          >
>          > I believe Sol later merged into Chorus was a reimplementation
>         in Pascal. I think this was a microkernel based system...
>          > I believe Locus distributed OS designed at UCLA was also Unix
>         compatible. I guess you can add Xinu as well as Amoeba to the list.
> 
>         I intentionally never looked at Locus source, but had much
>         interaction with Gerry Popek and Bruce Walker while I was at IBM
>         and they were working with IBM. I have a memory of Bruce telling
>         me they started with 4.1BSD, but I question that memory. Just
>         glancing at their book (https://www.penguinrandomhouse.com/
>         books/655167/the-locus-distributed-system-architecture-by-
>         gerald-j-popek/ <https://www.penguinrandomhouse.com/
>         books/655167/the-locus-distributed-system-architecture-by-
>         gerald-j-popek/>), the only cited Unix reference I see is the
>         1978 Ritchie/Thompson BSTJ paper. Section 1.5 Unix Compatibility
>         of their book says “For virtually all applications code, the
>         LOCUS system can provide complete compatibility, at the object
>         code level, with both Berkeley Unix and System V, …” I suspect
>         that the first Locus prototypes were based on BSD earlier than 4.1.
> 
>         Charlie
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