Int 2F/AX=BC00h/BX=3F3Fh

AX = BC00h
BX = 3F3Fh ('??')
CX = 0000h
DX = 0000h

Return:
If installed, BX XOR CX XOR DX = 4D56h ('MV')

Program: MVSOUND.SYS is a driver for the MediaVision ProAudio Spectrum family of sound boards; its primary programmer was Bryan Crane

See Also: Category: Sound/Speech - Int 2Fh - M