> > 	Sun 3/50
> > 	Wyse-50 monitor on ttyA
> ...
> 
> Note that setting the "Diag/Norm" switch to Diag mode forces the
> console interaction to ttya regardless of the EEPROM setting.

I don't have a 3/50 here, but on my 3/60 setting to Diag causes
extended POST diagnostic messages to appear on ttya (and I think on
ttyb also, but not on the display), followed by an invitation on all
three to invoke the extended test menu.  If you do so, the port you
did it from becomes the console until the next hard reset; if you
let it time out it reverts to the eeprom-defined device.

SunOS somehow finds out which port the ROM is actually using instead of
only looking at the eeprom setting, and ideally the console-steering
code in NetBSD-sun3 should do likewise.  Granted this is not very high
on the list of things to be done.