• Please review our updated Terms and Rules here

M8256 in PDP11/84 OK, in 11/04 fails (Grant)

braids

Member
Joined
Nov 12, 2010
Messages
44
Hi All,

I've tried to transfer a RX211 with RX02 from a PDP11/84 to a PDP11/04. When it works in 11/84 it boots without problems, but in the PDP11/04 (core) then the RUM light remains ON same time as a forgotten G727A or an open NPG. When i remove the M8256 and put a G7273 on that slot 6 then the machine works fine. There's also be three M7856 inside, one right and two at left side of the apropriate card. Can it be a AC load problem?

yours sincerly,

Braids.
 
Hi All,

I've tried to transfer a RX211 with RX02 from a PDP11/84 to a PDP11/04. When it works in 11/84 it boots without problems, but in the PDP11/04 (core) then the RUM light remains ON same time as a forgotten G727A or an open NPG. When i remove the M8256 and put a G7273 on that slot 6 then the machine works fine. There's also be three M7856 inside, one right and two at left side of the apropriate card. Can it be a AC load problem?

yours sincerly,

Braids.

When you say 'in an 11/84 it boots without problems' do you mean just the 11/84 (which is what I am assuming) or that you can boot and run from the RX211?

In the 11/04 the processor and memory are directly attached to the UNIBUS, so if it does not work the CPU will fail as you indicate.

In the 11/84 the UNIBUS sits behind a PMI bus to UNIBUS adapter, so nothing on the UNIBUS needs to work (including a console interface, which is on the CPU card) to boot.

So it may very well be the RX211 card is really dead and hosing the UNIBUS, which you will see on the 11/04, but not on the 11/84.

On the 11/84 can you read/write the RX211 I/O registers?

Don
 
When you say 'in an 11/84 it boots without problems' do you mean just the 11/84 (which is what I am assuming) or that you can boot and run from the RX211?

In the 11/04 the processor and memory are directly attached to the UNIBUS, so if it does not work the CPU will fail as you indicate.

In the 11/84 the UNIBUS sits behind a PMI bus to UNIBUS adapter, so nothing on the UNIBUS needs to work (including a console interface, which is on the CPU card) to boot.

So it may very well be the RX211 card is really dead and hosing the UNIBUS, which you will see on the 11/04, but not on the 11/84.

On the 11/84 can you read/write the RX211 I/O registers?

Don

i've got to try to boot RT11 from RX02 successfully. Can it be possible that the bootloader from PDP11/84 sacrifice for DMA or is that impossible?
Next days i will try an RL11 too.


Thank you,

Braids.
 
i've got to try to boot RT11 from RX02 successfully. Can it be possible that the bootloader from PDP11/84 sacrifice for DMA or is that impossible?
Next days i will try an RL11 too.

Thank you,
Braids.

Does this mean you booted RT11 from the RX02/RX211 on the 11/84 successfully, or that you want to try it and see if it is successful. Your wording is not clear to me.

RX211 is a DMA interface only, not possible to do all the I/O as programmed transfers.

Don
 
Does this mean you booted RT11 from the RX02/RX211 on the 11/84 successfully, or that you want to try it and see if it is successful. Your wording is not clear to me.

RX211 is a DMA interface only, not possible to do all the I/O as programmed transfers.

Don


After the failed test on the 04 i putted back the M8256 to 11/84 and after i typed "BOO DY0" the Floppy has pressed the heads on and i got the boot prompt of RT11 and the "."'s
I've also tested the RL11 on the 11/04, it dont locks but it is definitively deaf at the setted adresses.

Braids.
 
Could also be a backplane issue in your 11/04, such as contact corrosion. Some pins on the card may not be making a low impedance connection, resulting in an open circuit connection.

Moving cards around in slots (ie, try the RX211 in another slot, may require NPR grant jumper modifications) may help. Visual inspection, and/or a high quality contact cleaner like Deoxit.

I have an 11/34 with a nine slot CPU backplane, and a nine slot extension backplane. Several of the last SPC slots in the CPU backplane are marginal. If the system sits for a while I sometimes need to insert/remove the cards in those slots several times to get a good solid connection. Not even Deoxit helps as a permanent solution in my case. Requires physical slot manipulation.

Don
 
today i've put back M8256 into PDP11/04. now it works correct. There was probably a wiggle contact, but at foregoing test i've pulled the card and put back into slot and the problem wasn't gone.

Thank you.

Braids.
 
Back
Top