INT 1A - Tandy 2500, Tandy 1000L series - START PLAYING DIGITAL SOUND
        AH = 83h
        AL = volume (0=lowest, 7=highest)
        CX = number of bytes to play
        DX = time between sound samples (multiples of 273 nanoseconds)
        ES:BX -> sound data (array of 8-bit PCM samples)
Return: ???
Notes:  this call returns immediately while the sound plays in the
          background
        The sound data pointed to by ES:BX probably shouldn't cross a 64k
          boundary.  The BIOS appears to call INT 15/AX=91FBh when the sound
          device underflows to allow another INT 1A/AH=83h for seamless
          playing of long sounds.
SeeAlso: AH=84h,INT 15/AH=91h

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