27 Mar
2006
27 Mar
'06
2:23 p.m.
The 11/45 will boot xxdp+ v1, but won't boot RT11 v5.1.
Upon booting the RT11 v5.1 RL02 pack, the disk flashes for about 5-8
seconds, then the processor just halts.
First question which I didn't see in the RT11 5x docs... what exactly would
the hardware requirements be for RT11 5.1 on a 11/45? Is it expecting a
minimum of memory? Certain I/O devices at certain locations? I tried both a
real DEC RT11 v5.1 RL02 dist. pack, and also was able to gen one from a 5.1
image on a scratch pack with vtserver.
I have seen a 'stock' RT11 V5.something distribution boot on an 11/45. So
there's no inherent problem.
AFAIK the only devices that RT11 needs to boot are the system console (a
DL11 serial port at the normal addres (777560 IIRC)) and the disk
controller for whatever disk you are booting from (in yuor case an RL11).
These 2 devices need to be at the 'standard' I/O addresses and have the
standard vectors.
As regards memory, it doesn't need much. 32KW is easily enough. AFAIK
RT11 will boot on a system without mrmory management.
The only thing I can think of (and another listmember
point to as well) is a
problem with interrupts. But I've no idea how exactly to go about
troubleshooting it, not being a DEC expert like others here :) I've gone
back and forth between using 8K core, 16K core, or 128k unibus memory.
Similar results. My copy of xxdp+ seems a bit old, so most diags I have seem
to have older names.
Any thoughts are most appreciated!
Thougths (and be warned that I am not an RT11 expert)
Firstly, where does it halt? What's on the address lights when it halts.
If it appears to halt at the second word of a vector (that is, a location
near the start of the address space -- high bits all 0 -- with bit 1
set), then see if the first word of the vector points to that location
(it's common practice to set unused vectors to point to their own second
word, which contains a HALT instruction). If it does, then it reasonably
probable that the machine is taking that vector. Find out why. Is it ,
for example, an illegal address trap. Is it possible that some
interupting device is sending that vector.
Secondly, if the disk is being accessed for 5 seconds or more, it's
probable that something is being loaded from disk. Maybe you should step
through memory using the panel after it's booted to see if, indeed,
something is being loaded (and the data is not falling into a black hole,
which might indicate DMA problems). Does anything ever appear on the
console? Is it possible there's a problem with the console interface?
I've seen this sort of problem once on an 11/34. It halted when booting
RT11. It turned out that one of the DIP switches on the DL11-W console
interface card was defective, the card was therefore sending the wrong
interrupt vector. As soon as RT11 enabled interrupts on that device, it
got said bogus vector and halted (see above).
-tony