> On Aug 18, 2015, at 2:00 PM, Johnny Billquist <[email protected]> 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.
paul
