Probs w. M3119 CXY08 MUX on VAX VMS 7.3

Paul Koning paulkoning at
Tue Aug 18 14:29:36 CDT 2015

> On Aug 18, 2015, at 2:00 PM, Johnny Billquist <bqt at Update.UU.SE> wrote:
> On 2015-08-18 19:05, Jon Elson wrote:
> ...
>> Most likely, some board was added or removed from the system before you
>> got it, and it caused the vector to now be wrong.
> The vector is usually not the first victim. The CSR address is, which cause all access to the controller to fail. But the vector often also move, causing the more obscure errors. However, most DEC OSes actually autodetected the vetor, and did not care about the actual floating assignment rules for the vectors.
> The thing is, all you need is to trigger an interrupt on the device, and then notice at what vector it came in, and then you go with that. This only fails when several devices happen to use the same vector.

Typically that would be detected as a configuration error — two devices whose autodetected vector matches.  One of the offending devices (the one seen later, presumably) would end up disabled.

>> In some cases, you had to force a device to be at a non-standard
>> address, possibly because a 3rd party device could not be configured at
>> the address the DEC enumeration scheme wanted to put it at.  This was
>> pretty easy to do in later VMS systems.
> Very easy to do in RSX-11M-PLUS as well. A simple one line command, which can be done on the running system.

And RSTS, starting with V5B.


More information about the cctech mailing list