OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. The name stands for "Operating System/2", because it was intended as the preferred operating system for IBM's "Personal System/2 (PS/2)" line of second-generation Personal Computers.

OS/2 was intended as a protected-mode successor of MS-DOS and Microsoft Windows. Notably, basic system calls were modeled after MS-DOS calls; their names even started with "Dos" and it was possible to link text mode applications in such a way that they could work on both systems ("bound" programs). Because of this heritage, in terms of look, feel and features, OS/2 is not unlike Windows in many ways; but it also shares similarities with Unix.

Contents

1 Development history 2 Technology 3 See also 4 Quote 5 External links

Development history

OS/2 1.0 was announced in April and released in December 1987, as a text mode-only OS. It however featured a rich API for controlling the video display (VIO) and getting keyboard and mouse events, a sort of a protected-mode BIOS. Not surprisingly, the video and keyboard APIs were also available to "bound" programs on MS-DOS. The promised GUI, Presentation Manager, was introduced with OS/2 1.1 in November 1988.

The collaboration between IBM and Microsoft unravelled in 1990, between the releases of Windows 3.0 and OS/2 1.3. The increasing popularity of Windows prompted Microsoft to shift its development focus from OS/2, and IBM grew concerned about delays in development of OS/2 2.0. Initially, the companies agreed that IBM would take over maintenance of OS/2 1.0 and development of OS/2 2.0, while Microsoft would continue development of OS/2 3.0, then known as "NT OS/2". However, Microsoft decided to recast NT OS/2 as Windows NT, leaving all future OS/2 development to IBM. Windows NT's OS/2 heritage can be seen in its support for the HPFS filesystem and text mode OS/2 1.x applications (dropped in Windows NT 4.0 and Windows XP respectively).

OS/2 2.0, released in 1992, was touted by IBM as "a better DOS than DOS and a better Windows than Windows". Compatibility with these environments was achieved through virtual machines running several copies of the environment in parallel; this approach, which Microsoft adopted in Windows NT, provides better stability but also requires greater resources, especially memory. OS/2 2.0 also provided a new GUI called the Workplace Shell and a 32-bit API for native programs, though the OS itself was a mixture of 16-bit and 32-bit code (as Windows 95 would be).

OS/2 Warp 3, released in 1994, was a fully 32-bit OS. It offered a host of benefits, notably broader hardware support, greater multimedia capabilities, Internet-compatible networking, and a basic office application suite. In 1996, Warp 4 added Java and voice recognition software. IBM also released server editions of Warp 3 and Warp 4.

Overall, OS/2 failed to catch on in the mass market, and is today little used outside certain niches where IBM traditionally had a stronghold. For example, many banks, especially Automated Teller Machines, run OS/2 with a customized user interface; French SNCF national railways use OS/2 1.x in dozens of thousands of ticket selling machines. Nevertheless, OS/2 still maintains a small and dedicated community of followers.

Although shortly after the release of Warp 4, IBM began indicating that OS/2 would eventually be withdrawn, the company has not published a definite end of support date so far. The latest IBM version is 4.52 which was released for both desktop and server systems in December 2001. A company called Serenity Systems has been reselling OS/2 since 2001, calling it eComStation. The latest version is 1.2, released in 2004

IBM is still delivering fixes and updates on a regular basis. IBM urges customers to migrate their often highly complex applications to e-business technologies such as Java in a platform-neutral manner. Once application migration is completed, IBM recommends to migrate to a different operating system without giving any specific recommendations.

Even though some people had hoped that IBM would release OS/2 as open source, this is unlikely to happen since OS/2 contains much third-party code, much of it from Microsoft. Notably, although OS/2 2.0 is often believed to be IBM's own work, a beta version, accompanied by an SDK already had been released by Microsoft in the second half of 1990; OS/2 32-bit executable files have almost exactly the format of Windows 3.0 VxD device drivers (older 16-bit executables have the format of Windows executables). IBM seems mostly responsible for the GUI part of OS/2 (notably, the Presentation Manager API did not change in 2.0), and probably for the divergence in syntax and semantics compared to Windows. This was an underlying cause for the breakup between IBM and Microsoft when Windows 3.0 became much more successful than OS/2. However, open source operating systems such as Linux have already profited from OS/2 indirectly through IBM's release of the JFS file system, which was ported from the OS/2 code base instead of the AIX original.

OS/2 is virtually free of computer viruses. This is not due to its architecture. Its design could make it as vulnerable as Windows, if not more for the extensive scriptability, but probably its reduced mind and market share discourages virus writers. There are, however, OS/2-based antivirus programs, dealing with DOS viruses and Windows viruses that could go through an OS/2 server.

Technology

The graphic system has a layer named Presentation Manager that manages windows, fonts and icons. This is similar in functionality to a non-networked version of X11. On top of this lies the Workplace Shell (WPS), introduced in OS/2 2.0, which is an object-oriented shell allowing the user to access files and printers, and launch programs. WPS follows IBM's Common User Access user interface standards.

In recent years, IBM decided not to support the plethora of graphic cards, and licensed a reduced version of Scitech drivers.

WPS represents objects such as disks, folders, files, program objects, and printers using the System Object Model (SOM), which allows code to be shared among applications, possibly written in different programming languages. A distributed version called DSOM allowed objects on different computers to communicate. DSOM is based on CORBA. SOM is similar to, and a direct competitor to, Microsoft's Component Object Model. SOM and DSOM are no longer being developed.

OS/2 also includes a compound document technology called OpenDoc, which was a developed with Apple. OpenDoc is also no longer being developed.

The multimedia capabilities of OS/2 are accessible through Media Control Interface commands. The last update (bundled with the IBM version of Netscape Navigator plugins) added suport for MPEG files. Support for newer formats like PNG, progressive JPEG , DivX, OGG, MP3 comes from third parties. Sometimes it is integrated with the multimedia system, but in other offers it comes as standalone applications.

The TCP/IP stack is based on the open source BSD stack.

See also

• History of the graphical user interface
• REXX

Quote

"During the next ten years, millions of programmers and users will utilise this system" Bill Gates, November 1988.

External links

• IBM's official OS/2 page
• eComStation official site
• History of OS/2
• A Short History of OS/2
• netlabs.org - OpenSource Software for OS/2 and eCS
  • Nikipedia, the Netlabs wiki based on Mediawiki
• OS/2 FAQ (including version history details and marketing information)
• OS/2 Ezine (for OS/2 evangelism, news updates, and other articles)
• "OS/2" category in the Open Directory
• Some fundamental OS/2 concepts by Peter Moylan