[Info-vax] OS Ancestry

[Dave Froble]

On 5/17/2021 8:18 AM, Simon Clubley wrote:
> 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.
>

But is the implementation language the only issue?  I'd think not.  As 
John and minions have demonstrated, perhaps with some effort, they can 
handle the multiple languages.

Rather, perhaps it is the concepts that are different enough that it's 
apples and oranges, not two different types of apples?

For an example, FORK doesn't seem too easy to implement on VMS, 
regardless of the language.  Though, I'll admit that this example has 
little to do with your claim of ease of porting.

-- 
David Froble                       Tel: 724-529-0450
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