Revive 11/34

Jerry Weiss jsw at
Fri Dec 8 15:50:17 CST 2017

On Dec 8, 2017, at 2:25 PM, John Welch via cctech <cctech at> wrote:
> I am reviving an 11/34. Cards are:
> Back/Fans [M8266--------]  Front of machine where keypad is.
>           [M8265--------]
>           [M9312] [M7859]
>           [M7762--------]
>           [OPEN]  [M7860]
>           [M7840--------]
>           Bus grant in third from front slot
>           [M9302] [M7856]
> The 7856 is hooked to a cable/null modem (i think)/PC running XP&Hyperterminal
> When I first powered on the programmers console said '7' and I powered off, then back on, and now it says '5'
> Any suggestions as to what to try first?  I may have the bus grant in backwards.  I have other boards I can try.
> Sincerely,
> John Welch
> :qw

1) The G727A bus grant card is keyed (somewhat).     It should be in Row D (fourth from the back)
     It won’t seat evenly if reversed. At least that is what my scraped knuckles remember.     

     You can temporarily pull it out to finish the check out.  There’s nothing past the 
      M7840 that requires DMA.

2) Check the baud rate, stop bits and parity settings on both the Hyperterminal and the M785 to make sure they match. 
3)  Are you seeing a single 7 or 5 on  KY11-LB Programmer Console or on the Hyperterminal?
     An other status led’s lit on the KY11-LB?

4) I don’t see any memory listed…  Do you have any M7847’s?  

5) Grab a copy of EK-11034-UG-001 PDP-11-34 System User’s Manual for more info.


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