PDP-11/84 SLU problem?

Glen Slick glen.slick at gmail.com
Mon Dec 15 11:56:06 CST 2014

Here is one possible thing to check:


" Console Enable - The system console is enabled by setting
switch 1 to the off position. This also sets a 1 in register bit 7. If
the switch is in the on position, the system console is disabled and
bit 7 is reset to 0. If the system console is disabled, the output
line to the console is suppressed. Any input from the console results
in an error message to inform the user that the console is disabled."

Switch 1 is on the DIP switchpack next to the LEDs on the M8190
KDJ11-B CPU board. If you haven't checked that switch yet you might
want to make sure it is set to the off position, or just try toggling
it and see if it makes any difference in the console behavior. Switch
1 is also wired to 7 pin connector J3 on the M8190 CPU board. I don't
know if there is normally anything connected to J3 in an 11/84


On Mon, Dec 15, 2014 at 9:06 AM, John Rollins <kd7bcy at kd7bcy.com> wrote:
> So in function checking the PDP-11 now that the Series/1 is out of the basement and I have room to move the unit around and plug it in, I have discovered that it doesn't appear to transmit data from the console port on the back. I have tried two terminals(WY99) and two different PC's(Windows laptop with hardware serial port and a Mac with a USB adapter) with various software, a half dozen different cables, and every conceivable switch setting on the PDP with nothing to show for it aside from a lot of time spent the last couple of weekends.
> So when I power up, the LED display on the front counts down through the numbers and stops at 4. As near as I can tell, this is something of a good sign. But nothing ever comes up on a connected terminal. Sometimes pressing keys on the terminal results in the RUN light turning off, other times it does nothing. This would seem to indicate that the PDP knows that something is trying to talk to it, but it is not sending data out.
> Short of spending an entire day disassembling half the machine and tracing every wire hoping to find something out of place, does anyone have any ideas on what may be happening here, or what to look for?
> ------------
> John Rollins  |  KD7BCY  |  http://www.kd7bcy.com
> Ham-Mac mailing list http://mailman.qth.net
> ------------

More information about the cctech mailing list