INT 15 - Intel System Management Bus - REQUEST DATA AND STATUS

	AX = 53B0h
	BH = 13h
	BL = protocol (see #00487)
	CH = device address
	CL = device command
Return: CF clear if successful
	    AH = 00h (SMBus OK)
	    CH = status
		00h no data pending, transaction complete
		01h no data pending, transaction continues
		02h data pending
	    CL = number of valid bytes in DX (0-2)
	    DH = MSB data
	    DL = LSB data
	CF set if error
	    AH = error code (05h,10h,11h,13h,15h,16h,18h,1Bh,86h) (see #00484)
Desc:	determine when a transaction is complete, gather data returned by read
	  transactions
Note:	for Block Read protocol (08h), first call returns block	length in DH
	  and the first byte of the block in DL