[Info-vax] OS Ancestry

[Simon Clubley]

On 2021-05-15, <kemain.nospam at gmail.com> <kemain.nospam at gmail.com> wrote:
>
> Another pretty good link for those looking for VMS history:
>
><http://gordonbell.azurewebsites.net/digital/Bell_Retrospective_PDP11_paper_
> c1998.htm>
>
> "A Retrospective on What We Have Learned From the PDP-11:
> What Else Did We Need to Know That Could Have Been Useful in the Design of
> the VAX-11 to Make Alpha Easier?
>
> "VMS is the Architecture That Mattered. not PDP-11, VAX, or Alpha"
>

>From that link:

| Thus, our real oversight was not understanding that VMS should have been
| built on the C machine for portability across any architecture.

This. 5 zillion times this. VMS could have become like Unix in dominance
if this had been the case.

Want to move VMS to a new architecture in this setup ? It would have been
a comparable effort to what is involved in porting Linux to yet another
architecture, instead of the current effort that is involved.

VMS was designed at too low of an abstraction level.

Also, while he mentions BLISS, he skips over all the Macro-32 usage
and, based on discussions here, all the internal calling conventions
within the VMS kernel that requires those registers.

Simon.

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