FRSTOR          Restore saved state                  Exceptions: None
                                                     C3 C2 C1 C0: * * * *
FRSTOR source

        Logic   FPU state ← source

    FRSTOR reloads the FPU state (environment and register stack) from
    the memory area defined by the source operand. This data should have
    been written by a previous FSAVE or FNSAVE instruction.


    Note
    FRSTOR should be executed in the same operating mode as the
    corresponding FSAVE or FNSAVE. FRSTOR should be preceded with an
    FWAIT instruction to ensure that the storage operation is complete.
    If the state image contains an unmasked exception, loading it will
    produce an FP error condition.


    Opcode      Format
    DB /4       FRSTOR m94b     ; 16-bit code segment
    DB /4       FRSTOR m108b    ; 32-bit code segment


    Timing
    Variations/
    operand       8087         287        387      486     Pentium
    frstor  mem  (197-207)+EA 197-207     308    131/120   75-95/70 NP
    frstorw mem    -            -         308    131/120   75-95/70 NP
    frstord mem    -            -         308    131/120   75-95/70 NP

                  Cycles for real mode/protected mode