[Info-vax] DEC Multia (UDB) issues

[John Wallace]

On Aug 26, 9:11 am, Hans Vlems <hvl... at freenet.de> wrote:
> On Aug 23, 1:26 pm, MG <marcog... at SPAMxs4all.nl> wrote:
>
> > On 23-8-2011 12:39, Hans Vlems wrote:
>
> > > Running VMS on a Multia is not that difficult, even I managed to make
> > > it work. My Multia came with just 40 MB main memory IIRC and though
> > > VMS will boot and run in that limited space it halted within half an
> > > hour.
>
> > Which version did you run, do you recall that?
>
> VMS V7.3.
>
>
>
> > I'm a bit surprised, to be honest, that VMS wouldn't be able to handle
> > that.  Is it as simple that Alpha, being 64-bit, would ordinarily
> > require more RAM?  Or were you performing complex calculations, heavily
> > using DECwindows and therein based programs, perhaps?
>
> The 40 MB came in four boards: two 12 MB boards and two 8 MB boards.
> My conclusion after a
> couple of sudden stops of VMS (and that doesn't happen too often,
> right) was that either 40 MB was
> not enough to run X-motif in or perhaps that one of the memory boards
> was slowly going south.
> Then I learnt that AlphaServer 1000A boards fit in a Multia and after
> the memory upgrade the problems were over.
> So the cause is still uncertain.
> BTW a Multia is slow compared to an AlphaServer 300 4/266 system which
> has about the same internals.
>
>
>
> > I'm asking because most VAXen with even less memory will run just fine,
> > I've noticed (like some of the IPv7.net nodes).
>
> Correct but the memory requirements of 32 bit VMS and 64 bit VMS are
> quite different. Furthermore Alpha/VMS has
> functionality in it that just is not present in VAX/VMS. And VAX/VMS
> started life on a VAX 11/780 where memory capacity
> could be as low as 256 kB (entry level 128 kB perhaps!).
>
>
>
> > > The memory was expanded to 256 MB with memory boards with a height that
> > > only just fitted with the box closed. Well, you read about its cooling/
> > > airflow issues so the memory was reduced to 4 x 32 MB boards. It shares
> > > memory boards with the AlphaServer 1000A 5/xxx models.
>
> > There's a mere 32 MB in mine.  I don't think I really want to use the
> > system for anything else than a glorified DECterm (especially since my
> > LK463 works fine on it) to connect to my I64 cluster.  32 MB should be
> > fine for that, correct?
>
> Very likely, my Multia ran the DCE desktop on the graphics console and
> at the same time I ran an X-session on
> a PC with Reflection installed. And Motif is possibly not the easiest
> windows environment...
> If you just run the old style DECwindows kit, like the one that runs
> on top of VAX/VMS then 32 MB will work.
> Though adding memory is cheap (eBay) and any upgrade from 32 MB will
> be noticable.
>
>
>
> > > This works well, though its built in 10 Mb/s ethernet adapter slows it
>
> > Purely out of curiosity, since you brought this up: Are 100BASE-TX
> > ethernet adapters, since there's one PCI slot, available/known to work
> > in it?
>
> I have never dared to try! The Multia has cooling issues and I didn't
> want to install too much additional equipment in it.
> I also have an AlphaServer 300 which outperforms the Multia, so once
> VMS was installed I lost interest in the Multia.
> My study in the attic is small, has no airco and is fairly warm from
> april to september. So not an environment to keep a
> Multia in for daily work (a Digital Server 5305 does just that now).
> AFAIK there are no restrictions on what you can put on the Multia's
> PCI bus. A DE500 interface ought to work and wouldn't
> raise the inside temperature too much. YMMV.
>
>
>
> >   - MG
>
> Hans

"a Multia is slow compared to an AlphaServer 300 4/266 system which
has about the same internals. "

A Multia is indeed slow, but there are no other mainstream Alpha boxes
with "about the same internals" because there are no other boxes based
on the 21066/21068 CPU chip family used in Multia. The AlphaBook is
close though (and there were VME boards but that's a different story).

It's the 21066/21068 that is the main performance constraint in the
Multia, not what's around it, although having enough memory is
obviously important too.

The 21066/21068 has pretty much everything integrated onto the CPU
chip itself, apart from the SIMMs and the graphics and  and a handful
of PCI-derived IO (the PCI bus comes direct off the 21066/21068).
There is no off-chip northbridge/southbridge equivalent as used on
21064, x86, etc. The 21066/21068 is not quite an ARM-licencee-style
"system on chip" but it's a lot closer than an x86 or other Alpha
design would be.

Getting an x86-based Multia into the same form factor later in the
life of Multia was quite an achievement in its day, given all the x86
support electronics needed.