Int 15 Fn DA01  U - Ami Pci Bios - Cpu Speed Control                       [b]

   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