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1583

Category: BIOS

INT 15 - BIOS - SET EVENT WAIT INTERVAL (AT,PS50+)

	AH = 83h
	AL = subfunction
	    00h set interval
		CX:DX = microseconds to delay
		ES:BX -> byte whose high bit is to be set at end of interval
	    01h cancel wait interval
Return: CF set on error or function already busy
	    AH = status
		80h invalid command (PC,PCjr)
		86h function not supported (XT and later)
	CF clear if successful
Notes:	the resolution of the wait period is 977 microseconds on many systems
	  because many BIOSes use the 1/1024 second fast interrupt from the AT
	  real-time clock chip which is available on INT 70
	IBM AT 1984/1/10 BIOS ignores AL and always performs subfunction 00h
SeeAlso: AH=41h,AH=86h,INT 70,MEM 0040h:0098h,MEM 0040h:009Ch

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