21E4 INT 21 O - Novell NetWare - SET FILE ATTRIBUTES (FCB)
21E4 INT 21 - VIRUS - "Anarkia" - INSTALLATION CHECK
21E400 INT 21 - DoubleDOS - INSTALLATION CHECK/PROGRAM STATUS
21E400 INT 21 - OS/286, OS/386 - CHAIN TO REAL-MODE HANDLER
21E402 INT 21 - OS/286, OS/386 - SET PROTECTED-MODE TASK GATE
21E403 INT 21 - OS/286, OS/386 - REMOVE PROTECTED-MODE TASK GATE