wrote:

But is the compact flash card written with the Sandisk writer
similarly GPS unit specific? I cannot see how it could be. Is there
any way to write out a backup flash card for example (I have a spare
flash card from BK).

Yes, if I understand your question correctly, the card is BK-specific
because it has certain data (either topographical, man-made obstruction, or
both) on it that is placed there by BK, not by the process you will go
through every month when updating terminal data.

Also, the Sandisk reader requires special firmware for it to be able to
read and write BK data.

And finally, if you take the compact flash card out of the special-use
Sandisk reader and place it in another compact flash card reader, the OS
cannot access the card (as if it was not formatted).

--
Peter