Old thread closed http://www.keil.com/forum/59801/
naeem ahmad "So what is final verdict. Can we use NOR flash with Keil FAT FS or with open source FATfs library?"
Can they be used? Yes, that's not an issue of contention. Can you use them? That would really depend if you actually understood the problem.
The key issue is "write in place", the granularity of the FAT file system is typically much smaller than the erase block size of the media you are using. You must manage the read-erase-write in a manner that is efficient, safe, and within your memory budget.