INT 15 - BIOS - WAIT (AT,PS)
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
SeeAlso: INT 70

See also: 1583

1586 - BIOS - WAIT (AT,PS)