PDP-11/04-34 Programmer's Console manual error

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Mar 29 06:19:01 CDT 2016

So, something I just found out the hard way, while debugging another
'situation' with a PDP-11/04:

The KY11-LB Programmer's Console maintainence manual contains a major error,
in describing the configuration of the 20-conductor flat cable that connectors
the front panel and the UNIBUS interface module (M7859). This is covered in
Chapter 9, "Installation", which includes two figures, Figures 9-4 and 9-5.

Those figures show the 20-conductor flat cable with the red edge stripe
toward the outer edge of the front panel PCB (correct), and also toward the
outer edge of the M7859 (WRONG). On the M7859, the red stripe edge needs to
be oriented _away_ from the outer edge of the board. 

If it is plugged in as shown in these figures, the machine will not operate:
the four 'RUN/SR DISP/BUS ERR/MAINT' lights will be on, but nothing else, and
it will not respond to any keys. Fortunately, plugging the cable in reversed
does not damage anything; simply reverse the cable.


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