Microvax II 'primer'?

Warner Losh imp at bsdimp.com
Sun Jan 21 16:50:44 CST 2018

On Sun, Jan 21, 2018 at 3:04 PM, Rob Jarratt via cctalk <
cctalk at classiccmp.org> wrote:

> > -----Original Message-----
> > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jules
> > Richardson via cctalk
> > Sent: 21 January 2018 19:26
> > To: xx Classiccmp mailing list <cctalk at classiccmp.org>
> > Subject: Microvax II 'primer'?
> >
> >
> > So, I picked up (and I did just carry it into the house, and now I hurt)
> a
> Microvax
> > II from another list member yesterday. Cosmetically it's a disaster
> (BA123
> has a
> > cracked top panel, broken wheels, missing front door, missing right-rear
> panel)
> > but internally it appears to be complete; board wise we have:
> >
> >    M7606 - CPU
> >    M7608 - 4MB ram
> >    M9047 - grant continuity
> >    M7504 - DEQNA ethernet
> >    M3104 - DHV11 8-port serial
> >    M7555 - RQDX3 disk controller
> >    M7546 - TX50 controller
> >
> > ... it's got a TK50 and hard drive (no idea of capacity).
> >
> > Operational status is a complete unknown, and I have absolutely zero
> > knowledge about these systems - so my question at this stage is what
> > background reading I need to be doing in terms of pre-powerup* checks,
> > actually hooking a console, if there's a suggested minimal config I can
> use to
> > diag the CPU, and then (assuming it gets to that point) how to actually
> use the
> > thing (I'm assuming it was running VMS rather than Ultrix, but I don't
> know for
> > sure). I'm wondering there aren't any handy tutorials out there,
> alongside
> > whatever DEC docs are recommended.
> >
> > * e.g. for most machines I'd be thinking in terms of pulling all
> boards/drives,
> > hooking up a dummy load to whatever PSU rails required it, and then at
> least
> > running the PSU up in isolation first, but I don't know to what extent
> this
> > machine requires some logic in place for the PSU to even run.
> >
> > cheers
> >
> You might find that the filter capacitor goes up in smoke soon after you
> connect the PSU to the mains, even without powering it on. It doesn't
> actually do any damage and the PSU will continue to work (assuming it is
> just the filter capacitor). Check it, it is likely cracked and will soon
> go.
> If I remember correctly there are actually two of three of these (marked
> "RIFA"), it is probably a good idea just to replace them before they go.
> Otherwise it is certainly wise to check the PSU visually for any obviously
> failed electrolytics. If  you have one of the DEC load boards you could
> connect the PSU to that as a dummy load. I don't think there is much in the
> way of dependency on the CPU to run the PSU.
> Once you have the machine up and running the easiest thing to do is to boot
> it over the DEQNA by setting up a cluster on SIMH and making your MicroVAX
> II a satellite. I am not sure if 4MB is enough to do that though. Go with a
> 5.x version of VMS as I believe later versions may not support the DEQNA.

The DEQNA is obsolete (even by Q-bus standards), troublesome
<http://antinode.info/dec/deqna_settings.html#Troubles>, and not supported
by VMS <http://antinode.info/dec/deqna_settings.html#VMS_Support> since
about V5.4. A compatible card, the DELQA
<http://antinode.info/dec/delqa_settings.html>, replaces the DEQNA.

I was going to say VMS 4 is a better bet since 5 removed support, but looks
like 5.4 is the last version with support. Though the MicroVAX is UP, so
you might be better off with VMS 4 instead of VMS 5.


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