Need help with DSD-440 QBus Controller

[Jerry Weiss]

> On Sep 15, 2016, at 7:51 PM, Julian Wolfe <jrw at lolqb.us> wrote:
> 
> 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.
> 
See below.  Assuming you have a Q-Q backplane here.  If its an Q-CD, full stop.

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

Yes this is an 18 bit card, but it will work in a 22 bit Qbus in some OS’es (TSX+) with the correct configuration.    I.e. it will only move data to the between the lower 18bits of memory and media.  

> 
> 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.
> 

That is a good approach.   Using ODT make sure the CSR is at 17777170 (for an 11/73) or 777170 for an 11/23 and the status bits appear to be valid.

> 
> Any help with this card would be appreciated.  Am I doing something wrong, or is this just a bad card? 
> 
> 
A halt at 270 is a bit odd, but its only just above the interrupt vector. Disable the DSD controller on-board bootstrap.  Without drives and an OS disk, its going to halt at some point,

It will conflict with the UC07, if that is strapped for bootstrap as well.   Then try to boot your normal OS.
If RT11SJ, FB, or SB and the DY handlers are present, the machine should boot and the handler loadable.  Without the drives however, accessing them will not be useful.

Jerry