> The b dua9 did not work, but poking and jumping to the prom did (Thanks
> Emmanuel!).
>

The manual says to type

B/8 DUA9

This only works after a restart, or at least after an initialise and unjam.

My CE nose smells a rat here if b dua9 dosen't work (even without the /8 it should
do something.)  My first guess would be that the controller is set up in LSI-11
boot mode, where it jams the address 173000 onto the qbus after a BDCOK and tries
to run there.  To disable this, you should set switch 1-5 into the OFF position.
This might also explain your mcheck.

Regards,
Nigel Johnson, VE3ID