Troubleshooting RX02

[Rick Murphy]

At 03:41 PM 2/4/2005, Vintage Computer Festival wrote:

>In my continuing saga to get my PDP 11/03 working, I hooked up an MXV21
>(RXV21 clone, RX02 controller with formatting capabilities) with a
>standard set of 8" floppies.  I'm getting effectively the same results as
>with the DSD 440 though.  The heads load but nothing happens, and the
>system halts at 177204.

The head load happens when the boot starts because a clear is sent to 
the bus, resetting the drives. That's not an indication of much other 
than the fact that the controller and drive are talking to each other.

My guess: it sounds like the controller isn't working or isn't at the 
correct address.
You also might have a grant problem - are all the slots filled (with 
the correct serpentine path) between the CPU and the MXV21?

I would start with poking the CSR with the commands to read the first 
sector on the floppy by hand then checking for errors and looking to 
see what's been read off the floppy. The bootstraps aren't robust in 
the face of failure.
         -Rick