Yes. And I just want to point out the systems vendor's worst nightmare: Competition from an earlier version of their own product. History is littered with examples where something was deliberately left to wither and die for this reason.

Apple II and IIgs: We all know that the IIgs was deliberately crippled, and then discontinued in favour of the IIc+, as it presented a viable alternative to the 68000-based Macs.

680x0 Macs: Apparently some licensees had 68060 Macs and accelerators in the works, but Apple refused access to the ROMs to add the 68060 support code, because it would have been a viable alternative to the PowerPC 603.

IBM OS/2: Was heavily DOS based (I believe it used the INT 21h API with modifications for protected mode), but in fact was eclipsed by later versions of DOS/Windows that were retrofitted with things like DPMI support, hacky but effective in providing a viable alternative to OS/2.

BSD and SysIII: For a while it looked like the 32V-derived BSDs were going provide a viable alternative to AT&T's official developments of the same, and it took some heavy handed legal and political manouevring and backroom deals to make sure that did not happen in the end.

AMD64 and Itanium: Enough said, a very expensive egg on face episode for Intel. 8086/8088 and iAPX432: Same thing except it was actually Intel's own product that provided a viable alternative to the "official" new version rather than a competitor's development of it. Of course a similar story can be told about 8080/Z80/8085/8086, Intel faced stiff competition from an enhanced version of their own product before wresting back control with the much improved 8086. A nightmare for them.

That's the real reason vendors won't open source.

Nick

On Mar 4, 2017 12:02 PM, "Henry Bent" <henry.r.bent@gmail.com> wrote:
On 3 March 2017 at 18:56, Wesley Parish <wes.parish@paradise.net.nz> wrote:

And since the central Unix source trees have been static - I don't think Novell was much more than a
caretaker, correct me if I'm wrong - and the last SysVR4 release of any consequence was Solaris - has
Oracle done anything with it? - I think the best thing for all would be the release of the Unix SysV
source trees under a suitable open source license.

There was an SVR5, even if it was not nearly the popular product that its predecessors were.  While development certainly slowed, it contained some amount of technological progression.  Obviously at this point development has stopped completely and it probably does make sense to open source that code base.
 
(I've made a similar argument for the IBM/MS OS/2,
DEC VAX VMS, and MS Windows and WinNT 3.x and 4.x source trees on various other Internet forums:
the horse has bolted, it's a bit pointless welding shut the barn door now. Better to get the credit for
being friendly and open, and clear up some residual bugs while you're at it ... )
 
Equating VMS, old versions of Windows, etc. isn't quite the same.  Even old versions of those products may well include source that contains, or is believed by its owners to contain, novel ideas or novel implementations of existing ideas that may have survived relatively unchanged in newer versions.  And because there is at least a reasonably sized user base for all of the products you mentioned, corporate customers have an interest in protecting their investment, and the software creators have an interest in responding to the desires (or perceived desires) of their customers.

Don't get me wrong - I'd love to see a legal release of the VMS 5 source, or Windows 3 source, or classic Macintosh source.  I'm just not holding my breath.  I think the community's time would be better spend advocating for source releases of products that are truly dead or all but dead.

-Henry