Freebasic's "Out" function doesn't work as expected

[DirectuX]

Trying the example provided on the "Out"-keyword page of FreeBasic Manual, I noticed that there's no sound output. Explication is in the help file : Using true port access in the Windows version requires the program to install a device driver for the present session. The driver is only 3K in size and is embedded in the executable Obviously, the driver isn't embedded when the code is compiled to a *.dll

'speakersound.bas 
Sub Sound(ByVal freq As UInteger, dur As UInteger)
  Dim t As Double,f1 As Unsigned Short
    f1 = 1193181 \ freq
    Out &h61,Inp(&h61) Or 3
    Out &h43,&hb6
    Out &h42,LoByte(f1)
    Out &h42,HiByte(f1)
    t=Timer 
    While ((Timer - t) * 1000) < dur
      Sleep 0,1
    Wend
    Out &h61,Inp(&h61) And &hfc
End Sub

Sound(523, 60)  'C5
Sound(587, 60)  'D5
Sound(659, 60)  'E5
Sound(698, 60)  'F5
Sound(784, 60)  'G5
Sound(880, 60)  'A5
Sound(988, 60)  'B5
Sound(1046, 60) 'C6

To output a sound programmatically ( frequency , duration ) with thinBasic, this works. However, unlike old qbasic dialect, it makes a 'pause' between each instruction: no ramp (slope) is possible.