DEC OMNIBUS Signal Definitions

Rick Bensene rickb at
Fri Oct 17 16:34:16 CDT 2008

Hi, everyone,

I'm looking for a reference document that defines the functions of the
various signals on the DEC PDP 8/e/f/m Omnibus.
In Volume 1 of the Maintenance Manual, there is an Omnibus locator that
gives the names of the various signals and which pin on the backplane
each function exists on, but there's nothing that I can find that gives
the function definition of each of the signals.  The information is
buried in the test of the processor description, but there doesn't seem
to be a place that I can find that summarizes the information all in one

I'm troubleshooting a DEC RK8E disk controller that causes problems on
the Omnibus when the controller boardset is installed in an otherwise
fully operational PDP 8/e, and knowing what the various bus signals do
would make the task a whole lot easier.

Does anyone know of a document like this?

Rick Bensene

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