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

[Bob Sloane]

In article <12938 at steinmetz.ge.com>, davidsen at steinmetz.ge.com
 (William E. Davidsen Jr) writes:
>[lots of stuff comparing VMS and UNIX deleted]
> 
>   I still see no reason to think that non-portable operating systems are
> inherently faster or smaller than UNIX. ...
>
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,...? Does such
a thing really exist?  I mean one operating system that can run on several
different machines, UNCHANGED.  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."  What do you consider portable versus non-
portable?
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