https://www.pjrc.com/tech/8051/ide/fat32.html - ideal place to start, although a lot of parts are incorrect for FAT16
https://github.com/rweichler/FAT16test/blob/master/spec/FATLayout.pdf - good technical spec for FAT16 layout
https://github.com/rweichler/FAT16test/blob/master/spec/fatgen103.pdf - official Micro$osft FAT spec