AT&T Personal Computer 6300 DOS Release 2.0 (MS-DOS 2.11) 1984 AT&T MS-DOS (Version 3.30A) 1987 Microsoft MS-DOS (Version 4.00) 1988 Microsoft MS-DOS (Version 5.00) 1991 Microsoft Multitasking MS-DOS (Version 4.00) 1985 Microsoft IBM Personal Computer DOS (Version 2.00) 1983 IBM IBM Personal Computer DOS (Version 2.10) 1983 IBM IBM Personal Computer DOS (Version 3.00) 1984 IBM IBM Personal Computer DOS (Version 3.10) 1985 IBM IBM Personal Computer DOS (Version 3.20) 1986 IBM IBM Personal Computer DOS (Version 3.30) 1987 IBM Microsoft Windows Version 1.0 1985 Microsoft SCO XENIX System V release 2.1.3 for i8086 1986 SCO