INT 1A - TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)

	AH = 02h
	CF clear to avoid bug (see below)
Return: CF clear if successful
	    CH = hour (BCD)
	    CL = minutes (BCD)
	    DH = seconds (BCD)
	    DL = daylight savings flag (00h standard time, 01h daylight time)
	CF set on error (i.e. clock not running or in middle of update)
Notes:	this function is also supported by the Sperry PC, which predates the
	  IBM AT; the data is returned in binary rather than BCD on the Sperry,
	  and DL is always 00h
	MS-DOS/PC DOS IO.SYS/IBMBIO.COM use this function to detect if a RTC
	  is preset by checking if the returned values are non-zero. If they
	  are, this function is called one more time, before it is assumed
	  that no RTC is present.
BUG:	some BIOSes leave CF unchanged if successful, so CF should be cleared
	  before calling this function
SeeAlso: AH=00h,AH=03h,AH=04h,INT 21/AH=2Ch