(http://www.udayton.edu/~cps/cps560/notes/history/windows.html)

1983
Apple Computers introduced the Lisa computer in January 1983, and then set the standard for graphical environments with the Macintosh in January 1984.
Despite its declining market share, the Macintosh is still considered the standard against which all other graphical environments are measured.

1985
The first version Windows was released by Microsoft Corporation in November 1985. Over the next two years, Microsoft Windows version 1.0 was followed by several updates to support the international market and to provide drivers for additional video displays and printers.

1987
Windows version 2.0 was released in November 1987. This version supported several changes to the user interface. The most significant of these changes involved the use of overlapping windows rather than the “tiled” windows found in Windows 1.x. Windows 2.0 also included enhancements to the keyboard and mouse interface, particuliarly for menus and dialog boxes.

Up until this time, Windows required the only an Intel 8086 or 8088 microprocessor running in “real-mode” to access 1 megabyte (MB) of memory.
Windows/386, released shortly after Windows 2.0) used the “virtual 86” mode of the Intel 80386 processor to window and multitask many MS-DOS programs that directly access hardware. For symmetry, Windows version 2.1 was renamed Windows/286.

1990
Windows version 3.0 was introduced in May, 1990. The earlier Windows/286 and
Windows/386 versions were merged into one product with this release. The big change in Windows 3.0 was the support of the protected mode operation of Intel’s 80286, 80386, and 80486 microprocessors. This gave Windows and Windows applications acces to up to 16 MB of memory. The Windows “shell”
programs for running programs and maintaining files were completely revamped.
Windows 3.0 was the first version to become common on many users machinces, both in the home and the office.

1992
Windows version 3.1 was released in April, 1992. Several significant features included TrueType font technology (which brought scalable outline fonts to Windows), multimedia (sound and music), OLE, and common dialog boxes. Also, Windows 3.1 ran only in protected mode and required an 80286 or 80385 processor with at least 1 MB of memory.

1993
Windows NT, introduced in July 1993, was the first version of Windows to support the 32-bit programming model of the Intel 80386, 80486, and Pentium microprocessors. Windows NT has a 32-bit flat address space and 32-bit integers. Windows NT also supports long file names, like those allowed by unix systems.

1995
Windows 95 was introduced in August, 1995. Like Windows NT, Windows 95 supports a 32-bit programming model and long file names. Windows 95 provided a new user interface look, which was then transported to Windows NT Version 4.0.