Troubleshooting RX02

From: Rick Murphy <>
Date: Wed Feb 9 05:42:40 2005

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.
Received on Wed Feb 09 2005 - 05:42:40 GMT

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