The thing to do would be to see what happens if you load some multicast address (such as broadcast) into slot 0 of the 16-entry address match table, and the station address into slot 1. For a QNA, that's perfectly fine because all slots are equivalent and the device doesn't do any MOP. It may be that this was a later restriction that RSTS didn't obey. Or it may be a bad assumption in the real LQA that wasn't documented -- or maybe it's just a bad assumption in the SIMH emulation. I haven't yet looked for LQA manuals to give more clues. paul On Feb 15, 2013, at 8:53 PM, Johnny Billquist wrote: On 2013-01-24 20:29, Paul_Koning at Dell.com wrote: I was watching the MOP Console system ID messages from DECnet/E on simh, with an emulated LQA. Noticed something odd: the source address was broadcast. That's not valid, of course. The question is why that happened. The answer is that the emulation uses the address in slot 0 of the address filter as the source address. The hardware doesn't care what order the addresses go in as far as filtering is concerned; DECnet/E puts broadcast in slot 0 and the physical address in slot 1, followed by any multicast addresses. Is the SIMH behavior also what a real LQA does? That would be an interesting DECnet/E bug if so... Or does a real LQA just use the physical address, as a UNA would? Hi, Paul. Sorry for not responding sooner. Busy, as usual. However, I did mark this for some later investigation. However, I now realize that it's not trivial for me to test, as it would appear a RSTS/E system would help. :-) I honestly don't know how a real LQA do. Maybe John Wilson knows more, since he have been digging into these kind of questions way more than most people I know... Or else if you have some realistic suggestion on how I would test this on my machine, as I do have a 11/93 with a real LQA here (although an LQA plus). Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol