Re: need a bit of early boot help

On 2025-11-11 11:39, Anders Magnusson wrote:
> Den 2025-11-11 kl. 11:14, skrev Johnny Billquist:
>> On 2025-11-11 06:00, Mouse wrote:
>>> That may not be the relevant thing, though.  I don't know 1.6.1 in
>>> enough detail, but perhaps kernel output is polled but userland is
>>> interrupt-driven?  Maybe something is wrong with TXCS-driven
>>> interrupts?
>>
>> That would be the case, yes. Unless I remember wrong.
>> Since output from the kernel works, we can at least say that there is 
>> nothing wrong with the serial port as such. And the booting process 
>> went fine.
>>
>> And VMS also hangs after printing a banner... Which would suggest that 
>> there is something funny either with the printing on the console, but 
>> which is interrupt related, or something else is getting the machine 
>> stuck at an elevated privilege mode, preventing interrupts from being 
>> processed.
>>
>> I would actually probably suspect something else isn't completing, and 
>> the processor is stuck at some elevated prio. The console is probably 
>> working just fine, including when interrupt driven. But something else 
>> is not.
>>
>> I assume we're talking about a real machine here. So it has actual 
>> Unibus. Simple suggestions would be to remove everything not 
>> absolutely required to get the machine running, and really make sure 
>> you have bus grants in all Unibus slots not having a card in it. Also, 
>> make sure the NPR jumper is in place. This one can be a bit tricky, 
>> since it's actually a wire on the back side of the backplane, which 
>> might have been cut. There a double height bus grant cards that also 
>> covers the NPR signal, but the small square ones do not.
>>
>> And if the Unibus isn't properly configured, you can probably get 
>> things hung/stuck for some time.
> It's a 780, Unibus is not involved here at all :-)
> The PDP11 is connected directly to the backplane (SBI).

Well. Yes an no.
The PDP11, which is the FE, don't have any Unibus at all. And the 
machine boots, and there is terminal I/O to the console, and the system 
starts running.

But something happens somewhere along the way. And the *VAX* have a 
Unibus, and it will be probed somewhere along the way, and that is where 
I wonder what might be going on.

I don't think there are any problems at all with the PDP11 FE.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: [email protected]             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol