[Info-vax] OT: IA-128 ???

[VAXman- at SendSpamHere.ORG]

In article <4adb2f09$0$275$14726298 at news.sunsite.dk>, =?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne at vajhoej.dk> writes:
>glen herrmannsfeldt wrote:
>> Arne Vajh?j <arne at vajhoej.dk> wrote:
>> (big snip)
>>> A VAX is 32 bit because the application use 32 bit virtual addresses.
>>> Physical addresses is something else.
>>  
>>> I can not comment on PDP-11.
>>  
>>> I seem to recal that physical addresses of later VAX'es were bigger
>>> than 32 bit, but 40 bit sounds too much - that would be 4 TB of RAM.
>> 
>> I have sitting here the "VAX Architecture Reference Manual"
>> which includes specifications for some VAX.
>> 
>> The last one here is the 8800.  The "Physical address space" is,
>> of course, 32 bits, but only 29 bits address installed memory.
>> Above that is BI#0, multicast, boot ROM, reserved, node private space,
>> reserved, node 0 through node 15, reserved, BI#1 through BI#3, and
>> then more reserved.
>> 
>> So up to 512MB of actual memory.
>
>It was increased later.
>
>Some googling indicate that I remember wrong the increase of
>physical addressing was to 32 bits.
>
>Source:
>   http://labs.hoffmanlabs.com/node/131
>
>Arne

Late models of the VAX opened up the addressing to the full 32 bits.
This meant that you could have as much as 3.5 GB of physical memory.
512MB of the address space was still reserved for I/O.  4GB - 512MB.

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