Fxb is the format used by Fx-Interface to save backups. This format only allow one backup per file. Fxb files are ended by .fxb

Fxb are always build in the same way:

• 278 bytes (the first header of the file, maybe a lot of informations about the calculator)
• 10 0xFF characters (first separator)
• The “GY358” string (second header, always the same with a casio graph 65. Maybe the calculator model ?)
• 2 0xFF
• 6 bytes
• 9 0xFF (second separator)
• Raw data of the backup

You can see a header sample (all before raw data) in a hexadecimal view: fxbheader.txt