OS/2 and Windows 2.x
"Ironically, Microsoft is competing against itself in the operating systems market. Besides Xenix, Microsoft has announced Windows 386, which [is] somewhat similar to OS/2. Of course, either way users turn, Microsoft wins."
- Computerworld, 1987[18]
During the mid to late 1980s, Microsoft and IBM had cooperatively been developing OS/2 as a successor to DOS. OS/2 would take full advantage of the aforementioned protected mode of the Intel 80286 processor and up to 16 MB of memory. OS/2 1.0, released in 1987, supported swapping and multitasking and allowed running of MS-DOS executables.
IBM licensed Windows' GUI for OS/2 as Presentation Manager, and the two companies stated that it and Windows 2.0 would be almost identical.[19] By 1987 Computerworld said that Microsoft's Bill Gates "has pushed [Windows] almost fanatically for years", telling skeptical DOS software companies like Ashton-Tate and Lotus Development that developing for Windows was vital to compatibility with future DOS versions.[20] In a 1987 interview with Gates, Ed Esber of Ashton-Tate, and Jim Manzi of Lotus, Gates said that Microsoft would release Windows applications first with "very cheap upgrades" to OS/2 versions, while the others said that their companies would release for OS/2 first.[21] By then Microsoft gave more support to Windows software developers than those for DOS, providing marketing and new product release information.[22] Presentation Manager was not available with OS/2 until version 1.1, released in 1988. Its API was incompatible with Windows. Version 1.2, released in 1989, introduced a new file system, HPFS, to replace the FAT file system.
By the early 1990s, conflicts developed in the Microsoft/IBM relationship. They cooperated with each other in developing their PC operating systems and had access to each other's code. Microsoft wanted to further develop Windows, while IBM desired for future work to be based on OS/2. In an attempt to resolve this tension, IBM and Microsoft agreed that IBM would develop OS/2 2.0, to replace OS/2 1.3 and Windows 3.0, while Microsoft would develop the next version, OS/2 3.0.
This agreement soon fell apart however, and the Microsoft/IBM relationship was terminated. IBM continued to develop OS/2, while Microsoft changed the name of its (as yet unreleased) OS/2 3.0 to Windows NT. Both retained the rights to use OS/2 and Windows technology developed up to the termination of the agreement; Windows NT, however, was to be written anew, mostly independently (see below).
After an interim 1.3 version to fix up many remaining problems with the 1.x series, IBM released OS/2 version 2.0 in 1992. This was a major improvement: it featured a new, object-oriented GUI, the Workplace Shell (WPS), that included a desktop and was considered by many to be OS/2's best feature. Microsoft would later imitate much of it in Windows 95. Version 2.0 also provided a full 32-bit API, offered smooth multitasking and could take advantage of the 4 gigabytes of address space provided by the Intel 80386. Still, much of the system had 16-bit code internally which required, among other things, device drivers to be 16-bit code as well. This was one of the reasons for the chronic shortage of OS/2 drivers for the latest devices. Version 2.0 could also run DOS and Windows 3.0 programs, since IBM had retained the right to use the DOS and Windows code as a result of the breakup.
Microsoft Windows version 2.0 (2.01 and 2.03 internally) came out on December 9, 1987, and proved slightly more popular than its predecessor. Much of the popularity for Windows 2.0 came by way of its inclusion as a "run-time version" with Microsoft's new graphical applications, Excel and Word for Windows. They could be run from MS-DOS, executing Windows for the duration of their activity, and closing down Windows upon exit.
Microsoft Windows received a major boost around this time when Aldus PageMaker appeared in a Windows version, having previously run only on Macintosh. Some computer historians date this, the first appearance of a significant and non-Microsoft application for Windows, as the start of the success of Windows.
Like prior versions of Windows, version 2.0 could use the real-mode memory model, which confined it to a maximum of 1 megabyte of memory. In such a configuration, it could run under another multitasker like DESQview, which used the 286 protected mode. It was also the first version to support the High Memory Area when running on an Intel 80286 compatible processor. This edition was renamed Windows/286 with the release of Windows 2.1.
A separate Windows/386 edition had a protected mode kernel, which required an 80386 compatible processor, with LIM-standard EMS emulation and VxD drivers in the kernel. All Windows and DOS-based applications at the time were real mode, and Windows/386 could run them over the protected mode kernel by using the virtual 8086 mode, which was new with the 80386 processor.
Version 2.1 came out on May 27, 1988, followed by version 2.11 on March 13, 1989; they included a few minor changes.
In Apple Computer, Inc. v. Microsoft Corp., version 2.03, and later 3.0, faced challenges from Apple over its overlapping windows and other features Apple charged mimicked the ostensibly copyrighted "look and feel" of its operating system and "embodie[d] and generated a copy of the Macintosh" in its OS. Judge William Schwarzer dropped all but 10 of Apple's 189 claims of copyright infringement, and ruled that most of the remaining 10 were over uncopyrightable ideas.[23]
On December 31, 2001, Microsoft declared Windows 2.x obsolete and stopped providing support and updates for the system.
