Hi,

> Does anyone out there have something known to be an 83816?

WRAPs (http://www.pcengines.ch/wrap.htm) supposedly use DP83816. This is
listed on their page

  Connectivity: 	1 to 3 Ethernet channels (National DP83816), ...

and I can confirm that both my boards read DP83816 directly on the chip.
The interfaces come up as

  sip0 at pci0 dev 14 function 0: NatSemi DP83815 10/100 Ethernet, rev 00


> so I'm probably hosed at telling which is which, apart from the optimistic
> guess that, if the MAC address is all f's, there's probably no EEPROM.

Soekris boards use the same chip, but there have been issues where some
boards obviously left the manufacturer without testing and had no MAC
address programmed in. These showed up as all Fs as well. Just FYI.

Regards,

ND