Re: Larger memory option for VAXstations

[Johnny Billquist <bqt%update.uu.se@localhost>]

On 2015-08-20 23:20, Mouse wrote:
> > > 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.

Well, since the 25-bit PTE changes the interpretation of the PTE, it's 
something both the hardware and software have to agree on. It's 
implementation dependent in the way that not all processors will have 
it, but if they do, the interpretation when in 25-bit mode is not 
undefined, or implementation dependent.

And yes, there are systems which supports both flavors. Like I said, I 
have a VAX 7000-720 here, which is running with 1.25 Gig of memory...

$ sho mem
              System Memory Resources on 21-AUG-2015 12:52:31.08

Physical Memory Usage (pages):     Total        Free      In Use    Modified
  Main Memory (1280.00Mb)        2621440     2421905      195665 
 3870

Virtual I/O Cache Usage (pages):   Total        Free      In Use     Maximum
  Cache Memory                      7310          24        7286 
2495981

Slot Usage (slots):                Total        Free    Resident     Swapped
  Process Entry Slots                390         364          26 
    0
  Balance Set Slots                  351         327          24 
    0

Dynamic Memory Usage (bytes):      Total        Free      In Use     Largest
  Nonpaged Dynamic Memory       10485760     7742272     2743488 
7063808
  Paged Dynamic Memory           6010880     4632720     1378160 
4631024

Paging File Usage (pages):                      Free  Reservable       Total
  DISK$OVMSVAXSYS:[SYS0.SYSEXE]SWAPFILE.SYS 

                                               72000       72000 
72000
  DISK$OVMSVAXSYS:[SYS0.SYSEXE]PAGEFILE.SYS 

                                              311296      251478 
311296

Of the physical pages in use, 176256 pages are permanently allocated to 
OpenVMS.
$ show cpu

SIGGE, a VAX 7000-720
Multiprocessing is ENABLED. Streamlined synchronization image loaded.

PRIMARY CPU = 00
Active CPUs:      00 01
Configured CPUs:  00 01
$

	Johnny