21FE INT 21 - DOS v2.11-2.13 - OEM FUNCTION 21FE INT 21 - DoubleDOS - GIVE AWAY TIME TO OTHER TASKS 21FE INT 21 - VIRUS - "483" - INSTALLATION CHECK 21FE01 INT 21 - VIRUS - "Flip" - INSTALLATION CHECK 21FE02 INT 21 - VIRUS - "2468"/"Tequila" - INSTALLATION CHECK 21FE03 INT 21 - VIRUS - "2468"/"Tequila" - DISPLAY VIRUS MESSAGE 21FEAD INT 21 - VIRUS - "Shifting Objective" - INSTALLATION CHECK 21FEDC INT 21 - PCMag PCMANAGE/DCOMPRES - INSTALLATION CHECK 21FEDC INT 21 - VIRUS - "Black Monday" - INSTALLATION CHECK 21FEFE INT 21 - VIRUS - "CIDER" - INSTALLATION CHECK