Since RAM and flash are limited, the system uses "cramfs", which is a compressed rom based file system. A prototype file system is created on a linux host and them progressed into a cramfs image. The cramfs image is then written into the flash on the Ceiva picture frame.
The "UPDATE.sh" script will copy all the files into a prototype file system tree. It will try and untar the "proto.tar" file system but this will fail unless you are root. The device nodes can only be created by root. Once the device notes are in place the rest of the tree can be updated by non-root.
[aside: other programs like genextfs will create device nodes from a file and not require root; there may be a version of cramfs creation program out there which does this also but I'm not aware of one]
The "MAKE.sh" script actually creates the cramfs image file.
The "NOTES" file has the commands needed to send the cramfs image to the picture frame via hermit. It assume the image file name is "rootfs.img" which is what the MAKE.sh script creates.