Difference between revisions of "QBUS CPU ODT"

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Revision as of 17:08, 19 August 2019

ODT (Octal Debugging Technique) on QBUS PDP-11s is effectively their front panel. These CPUs do not have a front panel to control them; instead, as a cost-reduction measure, when the CPU is halted, specialized microcode uses the main serial line as a operating console. There are commands to read and write main memory, start the CPU, etc.

The command set is:

  • '/' - open location
  • '<CR>' - close open location
  • '<LF>' - open next location
  • 'G' - start CPU
  • 'P' - proceed CPU after halt

See also