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The PDP-6

History

The MI AI Lab traded in a PDP-1 for a PDP-6 in the mid 1960s and used it stand alone for some years. ITS was first written for this machine and it was operational in 1967. The following year a PDP-10 arrived, and it was arranged to share the I/O and memory buses with the PDP-6. The PDP-6 continued to be the main timesharing machine at first, with the PDP-10 as a subordinate processor. ITS was ported to the PDP-10 and eventually became the master.

The Dynamic Modeling group also received a PDP-6 in 1969, but quickly moved on to a PDP-10. Their PDP-6 never saw much use.

Simulator

Angelo Papenhoff's PDP-6 simulator is checked out in the tools/pdp6 directory. Using it is still in an experimental state. To run it, go to tools/pdp6/emu and run the pdp6 program. For shared memory to work, the KA10 simulator must be started first.

Stand alone operation

These programs work on stand alone on the PDP-6 simulator:

  • SYSTEM GEN - Marks a bootable Microtape.
  • MACDMP - Read, write, and start programs from Microtape.
  • TECO - Text editor.
  • MIDAS - Assembler.

Shared memory

When the PDP-6 simulator is properly configured and started after the KA10 simulator, the processors will share the PDP-6 core memory between them. ITS has a facility to create a job and have it's virtual memory range map to the PDP-6 core.

To make use of this, make a job named PDP6 or PDP10. The latter is from when the PDP-10 was the secondary processor. Reading or writing locations in this job will now access the PDP-6 memory. It's possible to load a program with $L or:LOAD. Starting, stopping, stepping, or setting breakpoints is not possible. These must be done from the PDP-6 console panel, or from DDT running on the PDP-6.