[Simh] VAX/VMS

[Timothe Litt]

On 16-Feb-16 06:49, Johnny Billquist wrote:
> More precisely, V7.3 will run on *any* VAX, including the primal
>> VAX-11/780. This level of backwards compatibility is unique.
>
> No, it is not. Talk to IBM about S/360... :-)
Agree
> And there are some VAXen on which V7.3 will definitely not run. How
> about rtVAX for example.
Not fair.  No version of VMS ever ran on rtVAX - it was designed that
way. (For yes, marketing reasons.)

Any version of VAX/ELN should run on all previous rtVAXen.

For those who don't know, rtVAX  is used in the Realtime market. 
VAX/ELN is the OS used
with it.  Another Cutler OS - written largely in PASCAL.  You build an
image on VMS, where it's
a layered product.  Then deploy to your embedded system, often with a
MOP boot.  (Yes, another
protocol that wireless usually doesn't route.)

It is exactly a VAX, except that process page tables are in physical,
rather than virtual memory.
The difference is that the process base register contains a physical
address, and microcode can
omit the virtual -> physical translation on a TB refill.

This was sold as a performance optimization for Realtime.  It was - but
it wasn't strictly necessary.

It really allowed market differentiation; rtVAX could be sold in
embedded systems at an
affordable (for the time) price point without cannibalizing the
minicomputer/data center machine
pricing.

(Former DEC Realtime and VAX architect.  And no, not responsible for
this decision.)


-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 4994 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://mailman.trailing-edge.com/pipermail/simh/attachments/20160216/02891edd/attachment.bin>