10 Feb
2009
10 Feb
'09
12:49 p.m.
Arhh, I had failed to grasp the difference between the G727A and G7273
cards. I had populated with G727A's (although I had left the RL11 in
place as I suspected as a DMA device it would need to be in place).
As I only had a single G7273, I instead put in an extended card and used
a multimeter to test the CA1->CB1 connections (I found this easier as
the wirewrap side of backplane is inaccessible on a 5.25" 11/34A). Found
3 slots had had their NPR connections removed.
I populated these slots with known working DMA cards (another RL11, a
RUX50 and a RX211) and powered up.. Sure enough run light now goes off
and I can key things into console.
After various card swapping I found that the original RL11 and the M7856
SLU had failed. Luckily I have spares for both of these cards.
I'll have another play later today to see if I can get the machine to
boot into its serial console and run a few basic test programs.
Many thanks for the help.
Toby
the problem in your 11/34 sounds like a non-continuous
grant chain.
Especially when you remove the terminator at the end, and the
system does not hang any longer!
Start with a minimal system. So the DD11-PK (first backplane)
only contains the 2 CPU boards, the M9312, the console interface
board M7859, and the SLU M7856 for the console terminal. Remove
the memory module, and put the terminator M9302 in the 9th slot,
in positions A-B.
Put in *all* other slots that have position C and D free a G7273 card.
(I hope you have those, you need 5 of them).
(I assume that are the cards you have in your 11/34)
With the G7273's you made sure that NPR grant chain is intact.
When you power up the /34, RUN should stay off, or pressing CTRL
and HALT should make it go off.
If you reached this condition, you can remove the G7273 from the slot
where you want to install the memory board and install the memory.
Test again.
Then remove one by one, one G7273 and replace it with a G727A, aka
knocklebuster. At a point the RUN LED will no longer go off. That slot
has the NPR wire (pin CA1-CB1 connection) cut. That is a slot you
can use for a "DMA" device like the RL11 interface. If that slot is not
used, you must have an G7273 inserted there, or a G727A *and* re-
wire pin CA1 to CB1.
In the end, some slots will have G7273's and some will have G727A's.
Needless to say, that for preservation of the hardware, switch off the
power before swapping even a module that has no components like the
G7273. And do not switch the system on within one or two seconds
after switching off. A few seconds delay will not hurt!
- Henk, PA8PDP.
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