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15DA01

Category: vendor-specific BIOS extensions
Flags: Undocumented function

INT 15 - AMI PCI BIOS - CPU SPEED CONTROL

	AX = DA01h
	CL = subfunction (00h-02h)
	    00h set low CPU speed
	    01h set high CPU speed
	    02h get current CPU speed
Return: CF clear if successful
	    AH = current/new CPU speed (00h low, 01h high)
	    AL = ??? (00h)
	CF set on error
	    AH = error code (86h unsupported subfunction)
Notes:	in the v1.00.05.AX1 BIOS, subfunctions 00h and 01h are NOPs in both
	  protected and V86 modes due to a test of MSW bit 0
	setting the CPU speed also generates the same audible signals generated
	  when manually switching speeds with Ctrl-Alt-Gray- and Ctrl-Alt-Gray+
BUG:	the BIOS apparently intends to return CF set if ???, but fails to use
	  a different exit path in that case, resulting in CF clear

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  Copyright 2000   by Ralf Brown     Updated Jul 2000