PDP-11/10 repair started

Jon Elson elson at pico-systems.com
Sun Oct 4 22:58:04 CDT 2015

On 10/04/2015 01:09 PM, Henk Gooijen wrote:
> Some corrections to my post regarding the console LED 
> behavior.
> Voltage levels on the CPU backplane are still good whne 
> the 2 CPU boards
> are installed in the backplane, but the processor is not 
> responsive to
> the switches on the console panel.
> The RUN LED is on, ADDRESS/DATA are all off.
You have no memory, and probably no devices to complete the 
Unibus. So, it is quite likely showing the Unibus is in a 
jammed state.  At the least, you need a Unibus terminator, 
and any bus grant cards between the CPU and the terminator 
(you'd have to check the manual to see how the Unibus is wired.)


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