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

[Johnny Billquist]

On 2012-03-23 18.45, Fritz Wuehler wrote:
> glen herrmannsfeldt<gah at ugcs.caltech.edu>  wrote:
>
>> Fritz Wuehler<fritz at spamexpire-201203.rodent.frell.theremailer.net>  wrote:
>>> Johnny Billquist<bqt at softjar.se>  wrote:
>>
>>>> No, the z/Arch, even in its latest implementation, does not give you 64
>>>> physical address pins out of the CPU, so no way you could hook up 2**64
>>>> bytes of physical memory.
>>
>>> Do you have a pinout handy? If so, I defer to you.
>>
>> As far as I know, they don't sell the chips separately from whole
>> machines, and don't publish data sheets. There might some
>> maintenance manuals, but likely not.
>
> If so we need to agree it's all conjecture and the architecture may support
> 64 bit physical addresses or it may not. If you don't have the pinout and
> the block diagram or some other documentation then nobody knows.

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.

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.

All claims for maximum physical memory on all machines I've seen so far 
are way below any 2^64 address range, and for some I have managed to 
find definitive information. The one I totally failed on was the z196. 
I'll totally agree that it's only conjecture, but based on the 
information I have managed to find, it looks like the max would be 64 
GB. That is way, way from 2^64...

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.

	Johnny