[TUHS] porting to different systems, Bootstrapping UNIX - how was it done

[Warner Losh via TUHS]

On Fri, Mar 27, 2026, 11:24 AM John R Levine via TUHS <tuhs at tuhs.org> wrote:

> On Fri, 27 Mar 2026, arnold at skeeve.com wrote:
> > If I recall correctly, the labs port was to an Interdata 8/32.
>
> Quite possibly.  Programming for the 7/32 and 8/32 were nearly the same.
>

Yes. Wollongong had the 7/32 and Bell Labs had the 8/32.

Warner


R's,
> John
>
> > John Levine via TUHS <tuhs at tuhs.org> wrote:
> >
> >> According to Noel Chiappa via TUHS <jnc at mercury.lcs.mit.edu>:
> >>> 2 - Move a set of existing software from one type of machine to
> another. (A
> >>> much more common event, now that we have portable software. Speaking of
> >>> portable software, I'm still amazed that this, which became one of
> Unix's
> >>> most important attributes, and a major driver in its spread, after V7,
> does
> >>> not appear to have been really thought about before V6/V7 was ported to
> >>> several other architectures.)
> >>
> >> I don't think it occurred to anyone until that that it would even make
> sense to
> >> move an operating system from one kind of computer to another.
> Historically,
> >> architectures were different, data formats were different, I/O
> architecture was
> >> different, and everything was written in assembler or maybe a language
> tied to
> >> the system like Burroughs Algol.
> >>
> >> By a decade after S/360 came out, computer architectures had all
> converged on
> >> 8-bit byte addressable two's complement designs with multiple
> registers. (Older
> >> machines like the PDP-10 weren't dead yet but it was just a matter of
> time.)
> >> Then Unix came along, written mostly in C which was highly portable to
> those
> >> 8-bit byte addressable machines. The group at the Labs allegedly picked
> the
> >> Perkin Elmer 7/32 because it was as different as possible from the
> PDP-11, but
> >> it wasn't all that different. It was 32 bits but the data formats were
> the same
> >> (give or take a few details of floating point), addressing and memory
> protection
> >> were similar to the PDP-11, and it had terminals and disks.
> >>
> >> Wollongong and the Labs separately did 7/32 ports, both probably
> observing
> >> that if they retargeted the C compiler to the 7/32 and recompiled the
> PDP-11
> >> C code, they were about 80% of the way there, so the rest of the work
> was
> >> a manageable project.
>