INT 80 - SoundBlaster SBFM driver - PLAY MUSIC
        BX = 0006h
        DX:AX -> music block
Return: AX = status
            0000h successful
            0001h music already active
SeeAlso: BX=0000h,BX=0007h,BX=000Ah,INT 1A/AX=FF04h

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