Need help with DSD-440 QBus Controller

[Julian Wolfe]

Hi folks,



I recently acquired a DSD-440 drive and purchased its accompanying controller on ebay.  The controller is configured at defaults according to the manual on Bitsavers.  However, unless it is on the bus by itself after the RAM cards, it halts the CPU at location 270.



Here are the 4 card configurations I tried, < or > denotes direction of serpentine QBus:



Doesn't work:


1 CPU - CPU - CPU - CPU >

2 RAM - RAM - RAM - RAM <

3 RAM - RAM - RAM - RAM >

4 RAM - RAM - RAM - RAM <

5 RAM - RAM - RAM - RAM >

6 DSD - DSD - RAM - RAM <

7 UC07-UC07- --DEQNA-- >

8 --- -  --- - --- - --- - --- <

9 --- -  --- - --- - --- - --- >



OR


1 CPU - CPU - CPU - CPU >

2 RAM - RAM - RAM - RAM <

3 RAM - RAM - RAM - RAM >

4 RAM - RAM - RAM - RAM <

5 RAM - RAM - RAM - RAM >

6 RAM - RAM - --- - --- <

7 DSD - DSD - --- - --- >
8 UC07-UC07- --DEQNA-- <

9 --- -  --- - --- - --- - --- >





Works (or at least leaves the CPU in the "RUN" state):



1 CPU - CPU - CPU - CPU >

2 RAM - RAM - RAM - RAM <

3 RAM - RAM - RAM - RAM >

4 RAM - RAM - RAM - RAM <

5 RAM - RAM - RAM - RAM >

6 DSD - DSD - RAM - RAM <

7 --- -  --- - --- - --- - --- >

8 --- -  --- - --- - --- - --- <

9 --- -  --- - --- - --- - --- >



OR



1 CPU - CPU - CPU - CPU >

2 RAM - RAM - RAM - RAM <

3 RAM - RAM - RAM - RAM >

4 RAM - RAM - RAM - RAM <

5 RAM - RAM - RAM - RAM >

6 RAM - RAM - --- - --- <

7 DSD - DSD - --- - --- >

8 --- -  --- - --- - --- - --- <

9 --- -  --- - --- - --- - --- >



The card says (C)1978 Data Systems Design on it, and the latest manual is (C)1980 - which makes me concerned this is an 18-bit only QBus card.



I have not yet tried attaching the drive box to the card, thinking it would at least see the controller without hanging.  The box isn't yet clean and ready to go.
 

Any help with this card would be appreciated.  Am I doing something wrong, or is this just a bad card? 



Thanks



Julian