A.63 FST, FSTP: Floating-Point Store

    FST mem32                     ; D9 /2                [8086,FPU]
    FST mem64                     ; DD /2                [8086,FPU]
    FST fpureg                    ; DD D0+r              [8086,FPU]
    
    FSTP mem32                    ; D9 /3                [8086,FPU]
    FSTP mem64                    ; DD /3                [8086,FPU]
    FSTP mem80                    ; DB /0                [8086,FPU]
    FSTP fpureg                   ; DD D8+r              [8086,FPU]

FST stores the value in ST0 into the given memory location or other FPU register. FSTP does the same, but then pops the register stack.