Re: Larger memory option for VAXstations

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> Is there an even more recent VARM out there?  [...]
> There was a `second edition' VARM edited in 1990 and released in
> 1991.  It mostly differs from the first edition by documenting the
> vector extension in the new chapters 12 and 13, and an annex B
> covering 37 different system models in the B.2 section.

The Revision J one I have describes vector extensions in capters 13 and
14 (chapter 12 documents virtual machines).  It also has an appendix B
"IMPLEMENTATION DEPENDENCIES" which documents 17 different models and
includes a note saying, basically, "we don't have enough people time to
chase down the differences among the models any more; please send us
the info", apparently addressed to other groups within DEC.

> It also describes the 21- and 25-bit PFN layouts in chapter 4, but
> does not describe which systems use 25-bit PFN and how to enable this
> mode on systems which support both flavours.

The document I have makes it sound as though there are no "systems
which support both flavours" - it's written as though the
interpretation of the low 25 bits of a PTE is an intrinsic property of
a particular VAX processor, just as tied to the implementation as (say)
whether MOVTC runs in hardware or takes an instruction-emulation trap.

> This is only documented in system-specific manual, such as the PAMODE
> IPR in the ``VAX 7000/10000 KA7AA CPU Technical Manual'',
> EK-KA7AA-TM.

...?  This is something I am going to have to investigate.  Thank you
for the pointer!

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