INT 21 - DOS 1+ - SET SYSTEM DATE
AH = 2Bh
CX = year (1980-2099)
DH = month
DL = day
Return: AL = status
00h successful
FFh invalid date, system date unchanged
Note:   DOS 3.3+ also sets CMOS clock
SeeAlso: AH=2Dh,INT 1A/AH=05h

See also: 212A

212B - DOS 1+ - SET SYSTEM DATE