mtd device clarification

Can someone clarify what these device files are:

/dev/mtd*
/dev/mtdblock*
/dev/nftla*

I have a 16MB DoC. My plan is to store a compressed root FS on the DoC flash and run the OS from ramdisk. I've erase the entire DoC, nftl_format the latter half of the DoC, make an ext2 FS on it, and copy the kernel there. I put my compressed root FS onto the flash section (first 8MB) with a 1024 offset:

# dd if=rootfs.gz of=/dev/mtd0 bs=1k seek=1024

I then tell the kernel where to get the rootfs

# rdev -r <kernel> 17408
# rdev <kernel> /dev/<which device file here?>

I've tried /dev/ramdisk, /dev/nftla and the kernel complains that it "Couldn't find valid RAM disk image at 1024".
I've tried /dev/mtdblock0 (as in HOWTO) and I get I/O error from end_request.

I've read the bootdisk HOWTO (for /dev/fd0) and I think I can do the same for the DoC if I can just tell the kernel where to get the compressed root FS. Thanks for any advice.

Dzuy