On Mon, 13 Jan 2020 at 16:43, Paul Winalski <paul.winalski@gmail.com> wrote:

>
> > Now my memory is a little hazy... I think OSF/1-386 used MachO
> originally,
> > but I've forgotten.   Switching the kernel to use ELF was one of the
> > differences between OSF1 and Tru64 IIRC.
>
> GEM never had to support Mach-O on any of its target platforms.  DEC's
> Unix on MIPS used COFF.  Tru64 used ELF exclusively.  I don't know
> what Apple used for object files before OS X.  IIRC NeXT was based on
> the CMU MACH microkernel and hence used Mach-O.  OS X is
> FreeBSD-based, but it uses Mach-O.
>

OSF/1 on MIPS used ECOFF by default, but at least some versions could also
create and run ELF executables.  That was all early to mid 1992, I
believe.  I don't have my DECstation up right now to check but I'm sure
that the OSF/1 2.0 beta can do it, and I wouldn't be surprised if the
versions of 1.0 with the v3.0 compiler could also do it.  I remember trying
to do ELF shared libraries but I think that support wasn't ready yet, which
is a shame because the ECOFF shared libraries on that platform are not fun
to deal with.  Not as bad as SGI's ECOFF shared libraries on IRIX 4
though.  I'm not sure if anyone outside of SGI ever bothered to put in the
work required to make one.

Wasn't OSF's original intent to use the OSF/ROSE object format?

-Henry