[Info-vax] DEC Multia (UDB) issues

[jjh]

On Oct 17, 9:33 pm, MG <marcog... at SPAMxs4all.nl> wrote:
> On 18-10-2011 0:10, John Wallace wrote:
>
> > The executive summary seems to be that you need 72pin 36bit true
> > parity (not fake parity) Fast Page Mode (not EDO) SIMMs, 70ns or
> > faster, installed in pairs. There is a Multia webpage at
> >http://www.brouhaha.com/~eric/computers/udb.html
> > which has Crucial part numbers listed. I would be surprised if these
> > are available new for a sensible price, but back in the day they were
> > in reasonably widespread use around the industry in general. Not as
> > widespread as the non-parity ones, mind you.
>
> Just my luck, there's nothing on the auction sites I frequently use...
>
> I don't feel like ordering overseas.  I don't even know if this thing
> will even work beyond the memory issues.  I still have the floppy error
> and the dead NVR/TOY to deal with, after all.  (Any ideas about the
> floppy diskette error, by the way?)
>
> > Another generic specification is in the Multia Service Information I
> > referenced earlier, and on page 91 of that document there are some
> > part numbers. Unfortunately although the 36bit parity SIMMs are not
> > Multia-specific, the DEC memory part numbers in the book *are* Multia-
> > specific - to ensure that the revenue was booked to the right business
> > unit, the very same SIMM could have various saleable part numbers,
> > depending on whose product it was to be used in.
>
> Thank you, I'll take a look at that.
>
> > Is it worth the effort? Only you can make that decision.
>
> I can only make that decision if I know what I can roughly expect and
> that's why I'm asking.  I apologize for not making that clear enough.
>
> > It is a miracle of technology, one which few other people will have
> > seen. Is it a useful tool for getting things done? In most cases you'd
> > be better off with the app on a sensible VMS box and the X kbd/mouse/
> > display on something more modern.
>
> Well, this is the best I can do at the moment.  Unless someone donated
> a nice AlphaStation, or AlphaServer (e.g. DS10, DS15/A) to me.
>
> Via the local UG/SIG I was promised a DS10, already in June, but that
> has not happened yet.
>
>   - MG

WRT FPM true parity memory, IIRC, they were use a lot in HP laser
printers of that era ( LJ4, LJ4+, LJ5, LJ6), so If you had one around,
that might serve as a useful source.  You would need to double check
the SIMMS in the machine for compatibility. Also, for some unknown
reason, HP used both EDO and FPM memory, so  you would have to check
which printer used what versions.
Also, HP played a game by having a non-standard Presence Detect (PD)
connections. I don't know if DEC did the same thing? Another issue you
would need to check.  The PD issue is addressed by soldering or
removing a jumper on the SIMM stick.
CAVEAT: This is from memory of 15-18 years ago so you would need to
double check the details...

Sorry about being non-specific, but perhaps it might spark others
memory...

-John