[Info-vax] Reimplementing VMS, was: Re: HP adds OpenVMS Mature Product Support beyond the end of Standard Support

[Johnny Billquist]

On 2014-02-03 19:44, JF Mezei wrote:
> On 14-02-03 04:17, Johnny Billquist wrote:
>
>> While I suspect that there was not much point in porting to the 32-bit
>> x86, any porting to 64-bit x86 would have little relation to multicore
>> and multiprocessor issues, since those are changing all the time anyway.
>
> Before 8086 gained quickpath/CSI, it had poor multi-core/multiprocessor
> scalability, something where IA64 had an advantage, and something which
> the BCS customer base looked for for large "mainframes".
>
> As a result, until x86 gained not only 64 bit but also good memory
> subsystem, there was no compelling reason for BCS customers to want to
> go to x86. Hence no good justification to spend money to evaluate ports
> to 8086.
>
> It is only once 8086 was announced to go 64 biuts and gained parity with
> IA64 with CSI/Quickpath (announcement in 2004) where porting might
> become viable.

And I disagree. While 64-bit was pretty much a requirement, the MP 
developments are (in my opinion) pretty much irrelevant here. These are 
implementation details for different chips, and new stuff can happen 
there without much change to the codebase. What happens to already exist 
in silicon is pretty irrelevant to the decision to port or not.

But moving back to a 32b-bit architecture would have been very unlikely, 
so until x86-64 started to spread, there was not much to look at. But 
once that happened, I am sure they did look at if it would be doable to 
port VMS. But given how much work it would be, it's not something that 
ever made sense from a business point of view until rather recently. And 
rather recently also means a much smaller custom base, which cannot 
support such a port anymore.

	Johnny