Ultrix & PDP/11 clock problems

[Jeff Giacobbe]

The following question is (I think) both a hardware and software one.
Here at the college (Montclair State) we offer on operating systems
class that uses a DEC Micro Vax and four PDP/11's.  The students write
their code on the MicroVax, then upload it to the PDP/11's for
execution, etc,etc,etc.

This system works fine for single-process programs. HOWEVER, when
trying to run code that uses concurrent processing, the system reports
back that the PDP/11's clock(s) is disabled.

We had DEC field-service out here the other day.  He checked all the
jumpers and connections on the PDP/11's and, as expected, everything
looked in it's proper place.  This led me to believe that it was a
software problem; i.e. there was some missing code that would turn on
the PDP/11's clock and provide the interrupts necessary to run the
concurrent processes.

The professors who have taught the class in the past tried out their
older concurrent-process programs that USED TO work.  Same thing: the
dreaded 'clock disabled' message.

So that's the situation, DEC field service says the hardware is
configured correctly and that it must be the software, the professors
say their programs worked before, so it must be a hardware problem!

Any help and/or suggestions would be GREATLY appreciated.

Thanks,

Jeff Giacobbe

giacobbe at apollo.montclair.edu   OR   giacobbe.pilot.njin.net