PDP11/23+ Error code question

[Paul Koning]

>>>>> "Jim" == Jim Beacon <jim at g1jbg.co.uk> writes:

 Jim> When the unit is powered up, there is no output to the terminal,
 Jim> and the processor fault LED's give a code of 14, which is listed
 Jim> as "Scope Loop" - does anyone know what this signifies?

"Scope loop" in DEC diagnostic terminology means a tight loop
repeating a single test (typically a failing test) indefinitely.
Typically that would be something not done by default, though I could
imagine a poweron selftest doing it by default when things are pretty
broken. 

The term is based on the notion that you'd be hammering the broken
thing fast enough that you could observe what was going on with an
oscilloscope (without needing stuff like a storage scope -- which
field service people did not carry).

      paul