[HECnet] Qbus ethernet spare?

[Paul_Koning at Dell.com]

On Jun 19, 2012, at 10:52 AM, Dave McGuire wrote:

On 06/19/2012 10:27 AM, Johnny Billquist wrote:
Found 1 DELQA and 4 DEQNA (condition unknown), and also have 1 broken
DELQA

I recall that the DELQA is more "modern" and better i some way, are they
also more prone to failure?

No. From a reliability point of view, I've not heard that either should
be better or worse. However, the DEQNA is rather buggy in its general
performance.

Side-by-side, the DELQA is quite a bit faster than the DEQNA, the
DELQA-YA ("Turbo DELQA") even more so.

That said, the DELQA has a "DEQNA compatibility mode"...whether that
makes it as slow and/or buggy as the DEQNA, I don't know.

I don't think so.

QNA compatibility mode means it works like a QNA from the driver point of view.   That was never the issue with the QNA -- if it had worked according to the specification, it would have been quite a good device.   The problem was that it never worked correctly, not even after 12 revisions.   Finally when rev L didn't work adequately either, the DEC software teams said enough is enough, we're dumping the QNA.

The issues were most obvious on VMS; I'm not sure if they were visible enough on the PDP11 OSs to cause concern.   Maybe with LAT, probably not or less so with DECnet.   I don't remember the details, other than that Local Area VAXclusters were the ones that tended to run into trouble, since those protocols were particularly unforgiving.

	paul