Int 1A Fn CCCC  U - Datefix - Installation Check                           [U]

   AX = CCCCh
   BX = CCCCh
   CX = 0000h

Return: CX = CCCCh if installed
       ES:BX -> original interrupt handler
Program: DATEFIX is a public-domain TSR to correct the date on AT&T 6300
     machines, where the realtime clock's calendar wraps after 1991

See Also: AH=FEh,AH=FFh"AT&T"