In a remarkable archaeological discovery, an unreleased build of IBM's OS/2 operating system, developed by Microsoft, has surfaced, providing valuable insights into the history of the partnership between the tech giants. The build, known as OS/2 2.0, was never released to the public but was extensively worked upon before Microsoft shifted its focus to Windows.

IBM's OS/2 project was meant to address the limitations of DOS and bring improvements such as better memory management, multitasking capabilities, and a user-friendly GUI. However, disagreements arose between IBM and Microsoft regarding the goals and demands of the operating system. While IBM aimed to enhance their own PCs by designing OS/2 around Intel's 80286 CPU limitations, Microsoft had its sights set on the booming market of PC-compatible clones.

Following the success of Microsoft's Windows 3.0 in 1990, the partnership between IBM and Microsoft dwindled, leading to the public release of OS/2 version 1.2, marking the end of their collaboration. Despite this, Microsoft had already made significant progress on OS/2 2.0, with preview screenshots appearing in PC Magazine and early builds being distributed to developers who were willing to pay the staggering price of $2,600.

Recently, software archaeologist Neozeed unveiled a stable internal preview of Microsoft's OS/2 2.0 on the Internet Archive. The preview, dating back to July 1990, offers a glimpse into the development and features of the unreleased OS. Neozeed's exploration of the build reveals its differences from the later 32-bit version of OS/2 2.0 that IBM eventually shipped in April 1992.

Although Microsoft's OS/2 2.0 remains a fascinating artifact from a critical juncture in PC history, it falls short as a functional desktop operating system. Its ability to run DOS and Windows applications simultaneously, a selling point at the time, proved to be a reason for developers to avoid creating OS/2-specific apps, contributing to the downfall of OS/2.

Interestingly, this recent discovery of the unreleased OS/2 2.0 build follows the earlier revelation of an early version of 86-DOS, the precursor to MS-DOS/PC-DOS, which Microsoft acquired and adapted for the IBM PC 5150. These discoveries serve as bookends for the complex and often-contentious relationship between IBM and Microsoft.

As part of their "divorce settlement," IBM took over the development and maintenance of OS/2 1.x and 2.x, while Microsoft pursued the creation of a more advanced OS/2 version 3.0. This version, however, never saw the light of day as OS/2 but eventually evolved into Windows NT, Microsoft's stable business-centric Windows version. Over time, Windows NT merged with consumer versions, resulting in the Windows operating system we know today.

Although IBM formally discontinued OS/2 18 years ago, a modernized branch called ArcaOS has emerged, offering intermittent updates and compatibility with modern hardware, as well as support for running MS-DOS and 16-bit Windows applications. This demonstrates that even discontinued software has the ability to find new life and adapt to the evolving technology landscape.