[Info-vax] OpenVMS I64 V8.1 "Evaluation Release"?

[glen herrmannsfeldt]

Johnny Billquist <bqt at softjar.se> wrote:

(snip)
> I'm still ready to claim that no machine produced today can connect 2^64 
> bytes of ram to it. I just don't see it as even probable that anyone 
> would be putting out 64 address pins.

Yes. It would be easy enough to add them when they are needed.
The architecture should be designed to allow for them, and even
should check that they are zero for now, but no need to implement
them yet.

> And that is ignoring possible architecture limits, where the machine 
> very well cannot form 64 bit physical addresses. After all, it is not 
> really required that a machine can form a 64 bit physical address, even 
> if you can form a 64 bit virtual address.

There should at least be the possibility. One could have alternate
forms for page tables, and use a smaller, more efficient form for now.

(snip)

> It would be interesting to hear if anyone with deep knowledge about the 
> architecture could comment on what the theoretical limits are on how 
> large physical addresses can be formed.

The z/ Principles of Operation is on the IBM web site. Last I knew,
they were reasonably priced, for the size, if you wanted to buy one.
Way over 1000 pages long.

-- glen