INT 21,2B - Set Date
AH = 2B CX = year (1980-2099) DH = month (1-12) DL = day (1-31) on return: AL = 00 if date change successful = FF if invalid date - sets DOS maintained clock - DOS versions 3.3+ also update the CMOS date where applicable
AH = 2B CX = year (1980-2099) DH = month (1-12) DL = day (1-31) on return: AL = 00 if date change successful = FF if invalid date - sets DOS maintained clock - DOS versions 3.3+ also update the CMOS date where applicable