DEC Professional 350 - video issue

Paul Koning paulkoning at
Fri Apr 10 14:57:17 CDT 2015

> On Apr 10, 2015, at 3:35 PM, John Ames <commodorejohn at> wrote:
> Back in November I dropped in on a list member's moving giveaway and
> came away with some DEC stuff, among which was a DEC Professional 350
> with keyboard and monitor. As the previous owner informed me, the
> video isn't working; there's no picture on the monitor, but there's
> visible sync lines, and the diagnostic lights on the back of the unit
> indicate an error with the bitmap graphics card. I'm pretty sure it's
> an issue with the card and not the slot, since the error moves with
> the card when I install it in one of the other slots, but I'm not sure
> what to look for on the card itself - nothing is socketed, so it's not
> chip creep, and the card connector looks to be in good shape.
> Does anybody have any advice for diagnosing and repairing this? 

Nothing from personal experience, unfortunately, but a few random notions:

I don’t remember if schematics for the -350 exist on-line, but the Technical Manual will at least give you detailed block diagrams.  It’s on Bitsavers.

If you have a console cable (which is basically a printer cable with a pair of pins on the PRO end jumpered together) you could try to boot an OS that will talk to a console terminal, then you might be able to use that to talk to the CSRs and dig deeper.  RSTS could do that but it’s not generally available; RT11 might, I’m not sure.  If you have some ODT-like program, you could poke around the CSRs and see what those tell you.


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