Function  2Bh  Set Date 
     set current system date 
entry   AH      2Bh 
	CX      year    (1980-2099) 
	DH      month   (1-12) 
	DL      day     (1-31) 
return  AL      00h     no error (valid date) 
		0FFh    invalid date specified 
note 1) On entry, CX:DX must have a valid date in the same format as returned  
	by function call 2Ah 
     2) DOS 3.3 also sets CMOS clock