Microvax II 'primer'?

[Rob Jarratt]

> -----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.

Regards

Rob