| I have two M3104 cards in my uVax-II.  I want to be able to use these
| serial ports.  What do I have to add in the kernel for these?

I don't have a DHV manual handy to check the DIP switch settings, but
I'd guess at least one must be set to the primary address.  The GENERIC
kernel has a line as follows (or at least when I look at my production
1.3.2/i386 system source that naturally has a VAX subtree):

	dhu0		at uba? csr 0160440	# DHU-11

Presuming you're running a GENERIC kernel, do you see a dhu0 message
at boot-time?

I'm pretty rusty, but there really is/was a DHU unit - it was Unibus based
I think.  Heck there was also a DH, a serious Unibus serial device - having
DMA support for serial lines was quite a serious serial device, over 20
years ago, at least to me! 8-)  Anyway, when the "toy" LSI bus turned into
Q-bus and started appearing in more serious hardware, "compatible" devices
like the DHV then the DHQ appeared.  Oh, just to keep you guessing, I
think a DH did 16 lines, so naturally a DHV/DHQ does 8 lines.  Ditto with
the more economical DZ Unibus board - it handles 8 lines so naturally
the DZV/DZQ (Q-bus versions) are four port based.  And while I'm likely
digging myself deeper with falsehoods and such, it is a tribute to my
favourite PDP-11's that they could somehow manage the horrendous interrupt
rate of the DV11J or DVJ11 or whatever else they decide to call it. Serial
boards without silos mean one must pay a lot of attention to them at high
speed... the DHV/DHQ are nice cards for their time I think - I believe
the DHQ at least can have a programmed delay on the silo going non-empty
- providing a form of high-water mark allowing the shared 256 byte silo
to fill more and leave the CPU to handle less interrupts per second (i.e.
by allowing more characters to enter the silo before triggering an Rx
interrupt).

I used to feel a little sad while playing with even the "modern" DHV
serial card and owning a "cheap" modem that could operate at a higher
data-rate... heck I even had to pull out an old Wyse-75 terminal because
unlike all my other dusty glass tty's it could manage 38.4Kb 8-)

-- Ken