Do OS's slow down with age? (was: DDJ article / UNIX vs BS/2)

[Doug Gwyn]

In article <2862 at kuhub.cc.ukans.edu> sloane at kuhub.cc.ukans.edu (Bob Sloane) writes:
>I have been looking for a portable operating system for some time. Does anyone
>know of one?  Unix?  Which version? BSD, SYS V, Ultrix, XENIX,...?

Almost any version.  If you have reasonable hardware SVR4.0 may be
your best bet, since it starts out already running on several widely
different architectures, implying that many of the porting problems
have been brought under control, and provides essentially a superset
of the other variants.  Xenix was merged into SVR3.2.  Some people
would prefer to port Mach, as Next has done.  For toy computers it
may be easier to port Minix or XINU.  4.3BSD has been ported more
than once.

>I mean one operating system that can run on several different machines,
>UNCHANGED.

Oh, get real!  What do you think an operating system DOES, anyway?

>While unix has been *modified* to run on quite a few different pieces
>of hardware, I am not convinced that it is "portable" and that VMS is
>"non-portable."

"Portability" is relative, not absolute.  UNIX (or, according to some
Bell Labs staff, "Unix"; definitely not "unix") can be and has many
times been ported to new, considerably different environments with far
less work than a total reimplementation would have called for.  That
has not been demonstrated for VMS, for reasons that are obvious to most.