[Info-vax] VMS internals design, was: Re: BASIC and AST routines

[Simon Clubley]

On 2021-11-24, Chris Townley <news at cct-net.co.uk> wrote:
> On 24/11/2021 21:45, Hunter Goatley wrote:
>> On 11/24/2021 1:14 PM, Simon Clubley wrote:
>>>
>>> VMS should have been designed 5-10 years later on than when it was.
>>>
>> 
>> In a thread of backpedaling inanities, that has to be the most inane.
>> 
>> Hunter
>
> +1
>

I am seriously annoyed by that comment Hunter because you have
completely missed (either accidentally or deliberately) the point
I am making (and have made before).

Compared to later operating system designs the internal design
of VMS is a direct product of the 1970s mindset because it is
ugly, hard to alter, not modular, full of internal hacks such
as jumping internally all over the place and was designed when
it was getting close to the end of when assembly language was
considered to be both an acceptable system implementation language
and an application language.

VMS has given us great things such as world-leading clustering,
but that doesn't change the ugly nature of its internal design.

This has caused major problems going forward as people tried to
enhance VMS. One such example is the need for a combined 32-bit/64-bit
address space.

Another such example is playing out right now as we speak.

The engineers at VSI are talented, experienced and generally skilled
overall. However, due to how VMS was designed, it has taken even these
skilled people over 7 years so far to port VMS to x86-64 and they will
not be finished until the middle of next year at the earliest.

As far as porting operating systems to a new architecture goes, that's
pathetic (but due to no fault of the above skilled engineers I hasten to add).

And even then, the port is not finished. After that, they need to provide
a filesystem that's suitable for today's hardware and today's disk sizes.

They have already had two goes at this and abandoned them. At current
schedules, you can easily add another couple of years for a new filesystem.

For comparison, I would expect a port of Linux to a new architecture to
take about 6-12 months to achieve first boot (if you also had to do
the compiler work as well) and about another 6-9 months after that
to deliver initial versions of the port into the hands of the customers.

How many people would have stayed with VMS if they knew in 2014 that
it would take another 8 years before they had VMS on x86-64 and another
couple of years after that before they had a filesystem suitable for
today's hardware ?

I say things that people don't like to hear. They are also the same
things that need to be said.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.