Why DEC doesn't need an ABI

[Brandon S. Allbery]

I believe we're all aware that DEC was denied an ABI for the VAX processor
line.  DEC was rather annoyed about it.  But I contend that DEC has no need
for a VAX ABI.

Why, you ask?

An ABI exists so that different manufacturers porting UNIX systems to a
particular processor can run the same programs, simplifying things for
applications developers.  Now:  it makes sense to do this for the plethora
of 80386 machines and 680x0 machines out there -- but for a VAX?  Consider
that (a) DEC does not license the VAX processor for anyone else's use, and
(b) DEC sells the only true commercial VAX UNIX.

The hardware question is obvious.  As for Unixes for a VAX, we have:  BSD
4.4 (it's a bit late to retrofit 4.[23] into an ABI, which also takes
mtXinu out of the picture), Mach, and (potentially) Gnu.  But Mach and
4.4BSD are *research* Unixes; as a result, they can experiment with new
applications interfaces, etc. and are not expected to follow a given ABI.
(They *could*, but in that case they would simply take the lead from DEC, on
whom they are dependent anyway because of the hardware.  Effectively, DEC as
source of the processor becomes a clearinghouse for OS work and defines a
de facto ABI.)  And I strongly doubt that Stallman would let a little thing
like an ABI get into his way....

Thus, for DEC to register an ABI would be pointless, and if so doing would
create work for AT&T that would have no effect on portability then AT&T has
no reason to accept a VAX ABI.
-- 
Brandon S. Allbery			  | "Given its constituency, the only
uunet!marque,sun!mandrill}!ncoast!allbery | thing I expect to be "open" about
Delphi: ALLBERY	       MCI Mail: BALLBERY | [the Open Software Foundation] is
comp.sources.misc: ncoast!sources-misc    | its mouth."  --John Gilmore