Any difference between VAX Q-bus and PDP-11 Q-bus cards?

Josh Dersch derschjo at
Thu Dec 7 01:45:48 CST 2017

On 12/6/2017 6:55 PM, Jon Elson via cctech wrote:

> On 12/03/2017 10:28 AM, Aaron Jackson via cctech wrote:
>> I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card
>> (M5976). If the card did not have the large metal face, would it work in
>> a Q-bus PDP-11? We are not going to potentially ruin a card by trying
>> this, but I am interested to know if this is the case.
> As long as the PDP supports the 22-bit Q-bus, it should work 
> perfectly.  The metal plate can be removed.
> Jon

The board will probably work in a 22-bit Q-bus, as you say, but only for 
certain values of "work" -- it won't catch fire or anything, but to the 
best of my knowledge the M5976 isn't an MSCP device and I don't know 
that any PDP-11 bootstraps or OSes know how to talk to it.  So unless 
you want to write a driver for it, it's probably not going to be much use.

- Josh

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