Windows 2.x

Windows 2.x is the second major version of Microsoft Windows, released in 1987. It was the first version to introduce support for enhanced features found in Intel's i386 processors. To differentiate it between the 8086-compatible version of Windows 2.x, the i386 version was sold and marketed separately under the "Windows/386" label. Two revisions of Windows 2.x exist, the original revision (2.0x) in generic "Windows" (8086/i286) and "Windows/386" variants, and a second revision (2.1x) marketed as "Windows/286" and "Windows/386" respectively. It was the successor to Windows 1.0 and was succeeded by Windows 3.0. Support for Windows 2.x ended on 31 December 2001, alongside its predecessor.

Currently, no pre-release builds of Windows 2.x are publicly available (though some have been confirmed to exist), and some retail versions remain unverified.

Development
Windows 2.0 was planned since at least April 1985 and started development shortly after the completion of Windows 1.01. The initial plan was for a point release, version 1.1. One of the primary complaints from those who used Windows 1.0 was the tiled window management, which many users found confusing. To solve this, support for overlapping all kinds of windows was introduced (up to this point, only dialog boxes could overlap other windows). This was toggleable at first, but the option was then removed entirely as the environment moved to overlapping windows exclusively.

By October 1986, the product had been renamed to Windows 1.5, and then again shortly after that to version 2.0, most likely as a recognition of the large changes that had been made as many new APIs had been added and parts of the kernel had been rewritten from C into assembly or vice versa. The product missed its initial release date of early 1987, though after that the development seems to have been fairly orderly with no large hiccups, and two alpha releases were sent to developers around May or June 1987, followed by two beta releases in July and August 1987.

At the same time as Windows 2.0, Microsoft were also working on a version of Windows designed to use the Intel 386's virtual 8086 mode to pre-emptively multitask MS-DOS applications in virtual machines. This product was completed first, possibly due to contractual obligations, and version 2.01 was released with Compaq DeskPro 386 machines in September 1987. After two months of further bugfixes and polishing, the new version was released to retail in both i8086 and i386 variants on 7 December 1987 as version 2.03.

The product was reviewed quite positively as a large improvement from its predecessor, with Windows/386 specifically singled out for praise, with the product winning a BYTE Award for "technical distinction" in January 1989. Over a million copies were sold by 1988, and although sales dropped somewhat in 1989, they still generally met internal sales targets (per antitrust documents) and nearly two million copies had been sold by January 1990. An increasing number of Windows applications were produced during this period, including the final completion of Word for Windows after a multi-year, infamously tortured development cycle in which the product missed over a dozen release dates and fell behind several Windows versions, as well as Excel for Windows.

New features
Windows 2.0 introduced support for overlapping windows for all window variants, while Windows 1.0 only supported overlapping of dialog windows. This fired a legal conflict with Apple Inc., accusing Microsoft and Hewlett-Packard of violating copyrights Apple held on Macintosh System Software. The judge ruled in favor of Microsoft and HP in all but ten of the 189 patents Apple sued for, which according to the judge couldn't be copyrighted.

This version of Windows also introduced support for VGA (Video Graphics Array) displays and PS/2 mice in the retail release, although drivers for Windows 1.0 have already been available in IBM's OEM release. It is possible to use the PS/2 mouse driver from Windows 2.03 with Windows 1.0, which enables one to use the virtual mouse emulated by many emulators and hypervisors.

Windows 2.11 added support for the AppleTalk protocol and the 8514/A display adapter.

Windows/386
Windows/386 is a variant of Windows 2 optimized for the 386 processor. It takes advantage of the virtual 8086 mode to preemptively multitask MS-DOS applications, although Windows itself still uses cooperative multitasking. Each MS-DOS instance runs in a separate virtual machine on top of a 32-bit virtual machine manager, which allows for better compatibility as they no longer share memory space with the rest of the environment. A bigger range of applications can also run in a window as opposed to the original variant, due to Windows/386 introducing grabber files that allow for better video emulation.

A modified version of Windows runs in the so-called System VM, a special virtual machine that controls the VMM and has access to all I/O devices by default. Both Windows and MS-DOS applications could also make use of EMS emulation provided by the virtual machine manager. However, swap is not supported and all running applications therefore have to fit into physical memory.

The original version was renamed to Windows/286 starting with version 2.1, which added the ability to use the high memory area (HMA) for an additional 64 KB of conventional memory with a 286 processor, although it does not necessarily require one and still runs on the original 8086 and 8088. The separate 386 variant was discontinued with Windows 3.0, which includes its functionality in the 386 Enhanced mode. The new Standard mode also carries over some of the MS-DOS support improvements, such as grabber files.

Control Panel myth
Contrary to popular belief, this version is not the first to include the Control Panel, a claim which at one point also appeared on Microsoft's own website. The Control Panel was already included with Windows 1.0 Development Release 5, compiled over 3 years before Windows 2.0 was released.

System requirements
According to Microsoft, the following are the recommended system requirements for Windows 2.x, including Windows/286 and Windows/386 releases. Windows 2.1 drops support for installing on two floppy disks and requires a hard drive to install Windows on.

This table takes account retail versions; OEM versions will vary depending on the hardware that it was intended to be installed on.

Compatibility
Windows 2.x does not officially support MS-DOS versions above MS-DOS 3.x due to a bug in the logo code that does not accept MS-DOS versions outside of MS-DOS 2.x and 3.x. All versions of Windows 2.x will crash on startup on MS-DOS 4.00 and above if  is not run on   to report a MS-DOS version between 2.00 and 3.31.

Additionally, 386 enhanced mode for Windows/386 will not boot on MS-DOS 5.x and above due to a conflict with HIMEM included in these MS-DOS versions. Windows will immediately exit if  is entered in these MS-DOS versions, and can only be booted via   in this case. Likewise,  cannot be loaded in a window if Windows is installed on MS-DOS 5.00 or above.

Easter eggs
All known versions of Windows 2.x include an updated version of the Windows 1.0 Easter egg, which shows a window with scrolling list of people that were involved with the development of Windows alongside a "Congrats!" button. Double-clicking the list box also changes the window background to tiled smiley faces. The sequence for triggering the Easter egg has changed since the previous version and is now activated by pressing F1, F5, F9, F4, and Backspace in quick succession.

The bundled version of Windows Write also includes an Easter egg, which inserts a picture with the list of people in the Write team. It can be activated by holding Ctrl and right-clicking the page number control.