I've been considering using a NANDrive by SST in a new design, however I wasn't sure how complicated it would be to connect a PIC to the ATA interface on the NANDrive. I did a quick Google search and found a couple of forums with people who had done it, but I was wondering if anyone here had experience with it and could suggest a standard software library for PIC C18 that implements ATA.
I wouldn't recommend it outside of an academic exorcise. You'll need 24pins (16 data 8 interface) and most likely bit bang the interface protocol as i don't think there is a PIC18 with any sort of 16bit parallel port. Bit banging the interface, managing the ATA command layer and managing the file system could consume almost all the PIC's time if your trying to get any sort of reasonable transfer rate.
If you really want to go this route a quick google search for "PIC IDE" came up with a few places to look for code that supports ATA/IDE on PIC's.
Alternately, interfacing to a SD card is really easy via a SPI port and there are PIC18's with SPI interfaces with DMA that would require much less work from the PIC to manage the interface.
If your worried about reliability there are industrial grade SD cards and board mount locking SD connectors.
Some 16-bit PICs have an 8/16-bit parallel port with up to 11 address lines. The PIC24FJ16GA002 is an example.