With 16 Floating Point Registers (FPRs), registers 0 to 7 are volatile, and registers 8 to 15 are non-volatile. That is, if a called routine uses any of FPRs 8 to 15, it must save those FPRs before use and restore them before returning to the caller. The called routine can use any of FPRs 0 to 7 without saving and restoring them. If the caller wants to keep data in FPRs 0 to 7, it must save those FPRs before a call and restore them afterward.