QBUS CPU ODT

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

• LSI-11 CPUs
• KDF11 CPUs
• KDJ11 CPUs