PDP-11/84 (KDJ11-B) and Error 61

Glen Slick glen.slick at gmail.com
Mon Feb 1 14:55:45 CST 2016

On Mon, Feb 1, 2016 at 12:24 PM, Ulrich Tagge <u.tagge at gmx.de> wrote:
> Hi List,
> I have a working 11/84, and I have decidec, to test some of my spare cards,
> starting with: KDJ11-B.
> I see the following error, when powering up the system, which points me to
> the Clock.
> Error 61
> M8190 clock Error
> Any hints, what the problem could be? Is the clock in this new PDP's still
> generated out of the line frequency? Could it by, that the KDJ11-B is
> configured to a wrong HZ value?

If you have one M8190 KDJ11-B which works fine and another one which
has this error when swapped into the same system you should check the
EEPROM configuration options between the two and see if the LTC
options are configured differently between the two.


Table 2-6 Configuration Parameters
H - Disable clock CSR (0)=No (1)=Yes
I - Force clock interrupts (0)=No (1)=Yes
J - Clock frequency (0)=Power supply (1)=50Hz (2)=60Hz (3)=800Hz

If the LTC parameters are configured differently between the two try
changing the parameters of the non working one to match the parameters
of the working one.

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