**Programming the PDP-6**

The AI lab PDP-10 shared its memory and I/O buses with a PDP-6.  The PDP-6 has 16K of core memory which the PDP-10 can also read and write.  The PDP-6 can not see the PDP-10 memory.  Both processors can send an interrupt to the other.

For ITS to talk to the PDP-6, the system location PDP6UP must first be set to -1.  To access the PDP-6 core memory from ITS, create a job named "PDP6" or "PDP10".  (Historical side note.  At first the roles were reversed: the PDP-6 was running ITS and the PDP-10 was the subordinate processor.)  This job will have a 16K core image and reads and writes will go directly to the PDP-6 memory.  DDT can load a program with $L.  It's not possible to start, stop, or set breakpoints.  These things will have to be done from the PDP-6 console.