Hi

>> 
>>   Incidentally, if I try to boot the machine from dua0 while closely
>> watching the LEDs on the drive (I'm pretty sure it's not bootable but
>> I just wanted to see if it'd try to execute a read), it sits there for
>> a few seconds and says "DEVOFFLINE".
>> 
>It your computer firmware says "DEVOFFLINE" then it's because it 
>fails to init the drive, not because you miss boot blocks. If you
>have a functioning disk without boot, then you will get another
>error message.

I had to add a KDA50 to a Q-bus machine a few weeks back and I found it
very useful to be able to do this with a MicroVAX III (KA650/KA655) CPU.
That way you can use SHOW DEVICE at the console to see whether the KDA50
can even talk to your drive(s). With the MicroVAX II (KA630) you don't
get this extra level of debugging.

The KDA50 LEDs may give you a clue. The diagram in the manual shows them as:


	====                            ==== handles
	+----------------------------------+
	|    o o o o +-----+ +-----------+ |	J3 40-pin
	|    8 4 2 1 | J3  | |    J1     | |	J1 50-pin
	|            +-----+ +-----------+ |
	|                                  |

	      rest of board  M7165

	M7164 LEDs are in a similar location.



What codes do you see on the two sets of LEDs?


I won't reproduce the whole table but one which has caught me out in
the past is:
0 = off	1 = on	x=on or off  B=blink

(Note: with board horizontal and viewed from the back of a BA23 cab
the LEDs are in the order 1,2,4,8

M7164   M7165   Error Symptoms			Most Likely Failure
LEDs    LEDs

8421    8421    


0011    0000    Hex 3: microcode halted in init See Note below

Note: most often seen during installation. This is the first point that
the KDA50 tries to access memory via the QBUS. Typical problems would include:

- QBUS routing (grant continuity problems)
- DMA access problem caused by faulty hardware other than KDA50 (if
  another DMA module works correctly in the same location, this is not
  likely).
- Check that preceding QBUS devices pass grant correctly
- If the preceding list does not catch the problem, try another M7164!

The LEDs usually start by cycling. This stops once the CPU starts talking
to the KDA50.

Hope this helps.

Antonio