PDP-11/23 Debugging

[Ben Sinclair]

Hi Holm, which behavior are you referring to? The CPU test?

I do find it strange that everything else seems to work great! I feel like
it should pass that test though.

On Tue, Nov 18, 2014 at 1:07 AM, Holm Tiffe <holm at freibergnet.de> wrote:

> Glen Slick wrote:
>
> > On Sun, Nov 16, 2014 at 7:44 PM, Ben Sinclair <bensinc at gmail.com> wrote:
> > > Well, I just discovered something interesting... What exactly does the
> aux
> > > switch on the front panel control? I assumed it was power to the AC
> plug on
> > > the back of the machine, but it must do something else. With aux in the
> > > down position, it again boots to XXDP! If I flip it up and restart, it
> > > drops back to ODT after trying to boot XXDP from the TU58.
> > >
> > > From the documentation, I don't see that it does anything other than
> > > control that AC plug.
> > >
> >
> > Take a look at the 11/03-L Front Panel schematic on page 19 of this
> > scan of the BA11-S Field Maintenance Print Set:
> >
> > http://www.bitsavers.org/pdf/dec/qbus/MP01233_BA11-S_schem_Mar81.pdf
> >
> > If jumpers W1 and W2 are installed on the front panel PCB then the
> > BEVENT line will be pulled down to ground when the AUX switch is in
> > the OFF position and I believe that will disable the CPU from
> > receiving LTC interrupts.
> >
> > Maybe your system is having issues handling LTC interrupts.
> >
> > I have one BA11-S with jumpers W1 and W2 installed on the front panel
> > PCB and another one with those two jumpers removed, so check your
> > front panel PCB to be sure whether or not they are installed, but it
> > sounds like they must be in your case if the position of the AUX
> > switch causes a behavior change.
> >
> > -Glen
>
>
> So far as I remember ifrom my own exeperiments this behavior is pretty
> much normal.
>
> Regards,
>
> Holm
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>


-- 
Ben Sinclair
ben at bensinclair.com