Int 15 Fn 86  - BIOS - Wait (at,ps)                                        [B]

   AH = 86h
   CX:DX = interval in microseconds

Return: CF clear if successful (wait interval elapsed)
   CF set on error or AH=83h wait already in progress
       AH = status (see AH=84h)

Note:  the resolution of the wait period is 977 microseconds on most systems
     because most BIOSes use the 1/1024 second fast interrupt from the AT
     real-time clock chip which is available on INT 70

See Also: AH=41h,AH=83h,INT 1A/AX=FF01h,INT 70