How do Unix and VMS compare?

[Guy Harris]

> >How many VMS ports to other CPUs/architectures compared to Unix
> >ports?

> Two (VAX and MicroVAX I).  By the fall the answer will be four (add
> VAX 11/790 and MicroVAX II).

How is the VAX-11/790 a different architecture?  How are the MicroVAXes
different architectures (except for having fewer instructions than the
other VAXes)?  The correct answer is "zero"; VMS hasn't been ported to
anything not running the MicroVAX instruction set or some superset.

> While this doesn't compare to the number of so-called Unix 'ports' (many
> of which have compatibility problems), I can bet my life that anything that
> runs on one VAX/VMS system will run unaltered on any other (without a
> recompile, even).  This is not my experience with Unix, nor should such an
> expectation be rational,

Such an expectation would not be rational if you include the "without a
recompile" clause, because binary code for a PDP-11 doesn't run on a
M68000 unless you write a simulator.

(By the way, if you write code that doesn't adhere to the VAX-11 architectural
standard - as was done *for UNIX* (the "printf" assembly-language
implementation) - you can write something that runs on one VAX/VMS system
and will not run unaltered on some others.)

> since an operating system, to be effective (*fast*, reliable, make full use
> of the hardware, etc.) must be closely knit to the hardware.

Closely knit in what sense?  Some UNIX ports aren't tuned for their hardware.
Some are.  Do you consider UNIX on a PDP-11 ineffective?  Do you consider
it ineffective on a VAX-11?  A SUN workstation?  Would you care to prove
your point by writing an OS for the SUN workstation (say) which is sufficiently
faster, and sufficiently more reliable, and which makes more complete use
of the hardware that it shows UNIX to be ineffective?

Please provide a detailed justification of why UNIX cannot be knit closely
enough to the hardware to be effective by your criteria.

> And VMS has EDT.

So?  UNIX has "vi" and EMACS, to mention two editors thought of very highly
by their devotees.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy