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

[Arne Vajhøj]

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