First off, thanks for the reply.

Would "Supported by the kernel" require a kernel module? lsmod lists nbd in my desktop kernel where the setup does work. lsmod does not show nbd in the n800 kernel, where I am having trouble.

However, I had to install the nbd-client package on the desktop machine (Kubuntu) to get the nbd-client command. The nbd-client command was already available in the busybox installation on the n800. I was assuming by its presence that the necessary bits were implemented, maybe or maybe not as a kernel module, by busybox... or maybe compiled into the kernel directly.

Plugging in the device amounts to issuing the nbd-client command which returns the "No such device or address" error.

Dmesg only shows many lines like this:
[362627.554687] menelaus 1-0072: Setting voltage 'VDCDC3' to 2800 mV (reg 0x07, val 0x29)

I don't think that's related. My display is screwed up, I think its a hardware failure in the graphics subsystem. I am using ssh to access the n800.

I think its useful life as a tablet is at an end, but I still have a lot to learn from it as a glorified network adapter, and general purpose device!!!

If I DO need a kernel module, there doesn't appear to be an nbd package for diablo, unless I can use a debian package compiled for the arm chip? If I have to make my own from sources I assume I will need to install the SDK and go from there? it will be a much longer journey than I intended, and take a while since this is a spare time kind of project - and likely require much more googleing and reading than installing!!

Thanks again for the reply, I at least have a direction to bumble and stumble now! Something to look into.