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

[VAXman- at SendSpamHere.ORG]

In article <jkpl8q$m3p$1 at Iltempo.Update.UU.SE>, Johnny Billquist <bqt at softjar.se> writes:
>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.

Why not?  If you used 1GB DIMMs, you'd only need 16,000,000,000 of them.

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