[Info-vax] DZQ11 on VAX/4000 Model 300

[John E. Malmberg]

On 1/15/2019 11:34 AM, Michael Moroney wrote:
> "John E. Malmberg" <wb8tyw at qsl.net_work> writes:
> 
>> All devices greater than BIRQ4 should be closer to the CPU than any
>> serial card, regardless of what the documentation states or you will
>> eventually get either a bugcheck or machine check.
> 
> I never encountered any devices that used other than BIRQ4.

I have used several.

>> All Q-bus serial cards that I have seen have a bug in that they only
>> pass the birq4 related signal from cards after them in the bus.
> 
>> Many 3rd party Q-bus disk controllers are BIRQ5.
> 
> Was there anything else that did so? Anything from Digital that did so?

DTQNA and the manual for it stated to put it after the CXYO8 cards. 
Guaranteed eventual crash.  And the interrupt driver for it did not 
save/restore R9, which occasionally upset something.

Regards,
-John