INT 2F - Kingswood TSR Windows - SOUND BEEPER
AX = 3901h
BL = 0Ah
DX = sound divisor, or 0 for silence.
(divide 1843200 by required frequency to get value for DX)
CL = sound length in 18.2 Hz clock ticks
Return: AX = error code (0000h if successful)

See also: 2F39

2F3901BL0A - Kingswood TSR Windows - SOUND BEEPER