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  by Bill Degnan - 06/16/2016 12:51
Tony Duell says in CCTECH:

"..What I would do is :

Check that there are transmit and receive clocks at the UART pins
(pin 40 and pin 17 IIRC). If missing, check the clock circuitry, crystal,
etc.

Check that there is a character strobe (I think the UART pin is
called 'TRL' -- Transmit Register Load) at the UART when you
try to write to the appropriate address. Make sure you don't
get a bus timeout error when you do that too. If that's
not right, check the address decoder, bus slave logic, etc

Check if there is any data coming out the UART on the Transmit
register output pin. If not (and if everything else is OK), suspect
the UART chip. But check it's not being held reset, it's getting
power, etc. ..


* * * *

One more source site:
http://iamvirtual.ca/col...nis/PDP11-10/M7800.html

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