This is of great importance to me as well, as I have an NEC Mobilepro 770
and recently acquired a Hitachi 4G Microdrive to use with Netbsd. NetBSD
does not recognize the drive.

After a little bit of searching around, I found that the problem stems
from the fact that Hitachi made certain Microdrives that are "IDE Only".
In the link below, you can see from their site that the only way to tell
is not from the model number, but the *part* number.

The good thing is that Hitachi openly provides all the technical specs you
can eat on these things, and I suspect that it's possible to get NetBSD to
recognize the drives. Unless of course, it's a hardware issue with the
Compact Flash controller.

It also looks like a serious "buyer beware" issue. I've heard through my
googling that a number of Ebay sellers will try to pass these off as
normal CF II cards without mentioning that they won't work in most CF II
compatible devices, and even go so far as to ship a cardreader with them,
just so they can say "Oh, but look, it works just fine!" I'm personally
one such victim.

Table of Hitachi 3K4 Microdrives, and what they are:
http://tinyurl.com/7mfx5

My question to the developers though, is "Can this be supported?" and
"Will it be supported?" It would be very cool if I could use this CF card,
instead of having to hunt down the anonymous Ebay seller and shaking the
change out of his pockets.