OS/2

OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 (PS/2)" line of second-generation personal computers. OS/2 is no longer marketed by IBM, and IBM standard support for OS/2 was discontinued on 31 December 2006.^[1] Currently, Serenity Systems International sells OS/2 under the brand name eComStation.

OS/2 was intended as a protected mode successor of PC-DOS. Notably, basic system calls were modeled after MS-DOS calls; their names even started with "Dos" and it was possible to create "Family Mode" applications: text mode applications that could work on both systems.^[2] Because of this heritage, OS/2 shares similarities with Unix, Xenix, and Windows in many ways.

Development history

Enthusiastic beginnings

The development of OS/2 began when IBM and Microsoft signed the Joint Development Agreement^[3] in August 1985.^[4] It was code-named "CP/DOS" and it took two years for the first product to be delivered.

OS/2 1.0 was announced in April 1987 and released in December. The original release was textmode-only and still lacked the GUI, which was added with OS/2 1.1 about a year later. OS/2 featured a rich API for controlling the video display (VIO) and handling keyboard and mouse events so that programmers writing for protected-mode no longer had to call the BIOS or access hardware directly. In addition, development tools included a subset of the video and keyboard APIs as linkable libraries so that family mode programs were able to run under MS-DOS. A task-switcher named Program Selector was available through the Ctrl-Esc hotkey combination, allowing the user to select among multitasked text-mode sessions (or screen groups; each could run multiple programs).^[5]

Communications and database-oriented extensions were delivered in 1988, as part of OS/2 1.0 Extended Edition: SNA, X.25/APPC/LU 6.2, LAN Manager, Query Manager, SQL.

The promised Graphical User Interface (GUI), Presentation Manager, was introduced with OS/2 1.1 in October, 1988.^[6] It had a similar user interface to Windows 2.1. The interface was replaced in versions 1.2 and 1.3 by a tweaked GUI closer in appearance to Windows 3.1.

The Extended Edition of 1.1, sold only through IBM sales channels, introduced distributed database support to IBM database systems and SNA communications support to IBM mainframe networks.

Version 1.2 introduced Installable Filesystems and notably the HPFS filesystem. HPFS provided a number of improvements over the older FAT filesystem, including long filenames and a form of alternate data streams called Extended Attributes.^[7] In addition, extended attributes were also added to the FAT file system.^[8]

The Extended Edition of 1.2 introduced TCP/IP and Ethernet support.

OS/2 and Windows-related books of the late 1980s acknowledged the existence of both systems and promoted OS/2 as the system for the future.^[9]

Breakup

The collaboration between IBM and Microsoft unravelled in 1990, between the releases of Windows 3.0 and OS/2 1.3. During this time, Windows 3.0 became a tremendous success, selling millions of copies in its first year.^[10] Much of its success was because Windows 3.0 (along with MS-DOS) was bundled with most new computers.^[11] OS/2, on the other hand, was only available as an expensive stand-alone software package. In addition, OS/2 lacked device drivers for many common devices such as printers, particularly non-IBM hardware.^[12] Windows, on the other hand, supported a much larger variety of hardware. The increasing popularity of Windows prompted Microsoft to shift its development focus from cooperating on OS/2 with IBM to building a franchise based on Windows.^[13] Several technical and practical reasons contributed to this breakup:

• Differences in culture and vision: Microsoft favored the open hardware system approach that contributed to its success on the PC; IBM sought to use OS/2 to drive sales of its own hardware, including systems that could not support the features Microsoft wanted. Microsoft programmers also became frustrated with IBM's bureaucracy and its use of lines of code to measure programmer productivity.^[14] IBM developers complained about the terseness and lack of comments in Microsoft's code, while Microsoft developers complained that IBM's code was bloated.^[15]

• Differences in API: OS/2 was announced when Windows 2.0 was near completion, and the Windows API already defined. However, IBM requested that this API be significantly changed for OS/2.^[16] Therefore, issues surrounding application compatibility appeared immediately. OS/2 designers hoped for source code conversion tools, allowing complete migration of Windows application source code to OS/2 at some point. However, OS/2 1.x did not gain enough momentum to allow vendors to avoid developing for both OS/2 and Windows in parallel. IBM's involvement was much more successful in redefining Windows' visual appearance after the 1.0 release, giving it what is today perceived as the "Windows 3.0 look".

• OS/2 1.x targeted the 80286 processor: IBM insisted on supporting the Intel 80286 processor, with its 16-bit segmented memory mode, due to commitments made to customers who had purchased many 80286-based PS/2's because of IBM's promises surrounding OS/2.^[17] Until release 2.0 in April 1992, OS/2 ran in 16-bit protected mode and therefore could not benefit from the Intel 80386's much simpler 32-bit flat memory model and virtual 8086 mode features. This was especially painful in providing support for DOS applications. While, in 1988, Windows/386 2.1 could run several cooperatively multitasked DOS applications, including expanded memory (EMS) emulation, OS/2 1.3, released in 1991, was still limited to one 640 kB "DOS box".

Given these issues, Microsoft started to work in parallel on a version of Windows which was more future-oriented and more portable. The hiring of Dave Cutler, former VMS architect, in 1988 created an immediate competition with the OS/2 team, as Cutler did not think much of the OS/2 technology and wanted to build on his work at Digital rather than creating a "DOS plus". His "NT OS/2," was a completely new architecture.^[18]

IBM grew concerned about the delays in development of OS/2 2.0 and the diversion of IBM funds earmarked for OS/2 development towards Windows. 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. In the end, Microsoft decided to recast NT OS/2 3.0 as Windows NT, leaving all future OS/2 development to IBM. From a business perspective, it was logical to concentrate on a consumer line of operating systems based on DOS and Windows, and to prepare a new high-end system in such a way as to keep good compatibility with existing Windows applications. While waiting for this new high-end system to develop, Microsoft would still receive licensing money from Xenix and OS/2 sales. Windows NT's OS/2 heritage can be seen in its initial support for the HPFS filesystem, text mode OS/2 1.x applications, and OS/2 LAN Manager network support. Some early NT materials even included OS/2 copyright notices embedded in the software. One example of NT OS/2 1.x support is in the WIN2K resource kit. OS/2 support also includes Presentation Manager support with the addition of the Windows NT Add-On Subsystem for Presentation Manager.^[19]

32-bit era

OS/2 2.0 was released in April 1992. It provided a 32-bit API for native programs, though the OS itself was a mixture of 16-bit and 32-bit code. It included a new GUI environment called the Workplace Shell. This was a fully object-oriented GUI that was a significant departure from the previous GUI. Rather than merely providing an environment for program windows (such as the Program Manager), the Workplace Shell provided an environment in which a user could manage programs, files and devices by manipulating objects on the screen.

DOS compatibility

OS/2 2.0 was touted by IBM as "a better DOS than DOS and a better Windows than Windows".^[20] For the first time, OS/2 was able to run more than one DOS application at a time. This was so effective that it allowed OS/2 to actually run a modified copy of Windows 3.0, itself a DOS extender, including Windows 3.0 applications.

Because of the limitations of the Intel 80286 processor, OS/2 1.x could run only one DOS program at a time, and did this in a way that allowed the DOS program to have total control over the computer. A problem in DOS mode could crash the entire computer. In contrast, OS/2 2.0 could benefit from the virtual 8086 mode of the Intel 80386 processor in order to create a much safer virtual machine in which to run DOS programs. This included an extensive set of configuration options to optimize the performance and capabilities given to each DOS program. Any real mode operating system (such as Xenix) could also be made to run using OS/2's virtual machine capabilities, subject to certain direct hardware access limitations.

Like most 32-bit environments, OS/2 could however not run protected-mode DOS programs using the older VCPI interface, unlike the Standard mode of Windows 3.1; it only supported programs written according to DPMI. (Microsoft discouraged the use of VCPI under Windows 3.1, however, due to performance degradation.^[21])

Unlike Windows NT, OS/2 also always gave DOS programs the possibility of masking real hardware interrupts, so any DOS program could deadlock the machine this way. OS/2 could however use a hardware watchdog on selected machines (notably IBM machines) to break out of such a deadlock. Later, release 3.0 leveraged the enhancements of newer Intel 486 and Intel Pentium processors — the Virtual Interrupt Flag (VIF), which was part of the Virtual Mode Extensions (VME) — to solve this problem.

Windows 3.x compatibility

Compatibility with Windows 3.0 (and later Windows 3.1) was achieved by adapting Windows user-mode code components to run inside a virtual DOS machine. Originally, a nearly complete version of Windows code was included with OS/2 itself: Windows 3.0 in OS/2 2.0, and Windows 3.1 in OS/2 2.1. Later, IBM developed versions of OS/2 that would use whatever Windows version the user had installed previously, patching it on the fly, and sparing the cost of an additional Windows license.^[22] It could either run full-screen, using its own set of video drivers, or "seamlessly," where Windows programs would appear directly on the OS/2 desktop. The process containing Windows was given fairly extensive access to hardware, especially video, and the result was that switching between a full-screen WinOS/2 session and the Workplace Shell could occasionally cause issues.^[23]

Because OS/2 only ran the user-mode system components of Windows, it was not compatible with Windows device drivers (VxDs) and applications needing them.

Multiple Windows applications ran in a single Windows session, just as they would under native Windows. To achieve true isolation between Windows 3.x programs, OS/2 could run multiple copies of Windows in parallel. This approach required considerable system resources, especially memory. It was possible to use DDE between OS/2 and Windows applications, and OLE between Windows applications only.^[24]

The "Warp" years

OS/2 version 3.0, released in 1994, was labelled as OS/2 Warp to highlight the new performance benefits, and generally to freshen the product image. "Warp" had originally been the internal IBM name for the release: IBM claimed that it had used Star Trek terms as internal names for past OS/2 releases, and that this one seemed appropriate for external use as well.

At the launch of OS/2 Warp in 1994, Patrick Stewart was to be the Master of Ceremonies; however Kate Mulgrew^[25] of the then-upcoming series Star Trek: Voyager was substituted at the last minute.^[26]

OS/2 Warp offered a host of benefits over OS/2 2.1, notably broader hardware support, greater multimedia capabilities, Internet-compatible networking, and it included a basic office application suite known as IBM Works. It was released in two versions: the less expensive "Red Spine" and the more expensive "Blue Spine" (named for the color of their boxes). "Red Spine" was designed to support Microsoft Windows applications by finding and using Windows already installed on the computer's hard drive. For this reason, the Red Spine version was also known informally and humorously as the "Ferengi" version, a reference to the Star Trek character species, because of this version's "acquisition" of existing MS Windows installations to increase OS/2's usefulness and appeal, much as a Ferengi might do. The nickname was also an homage to its immediate predecessor, "OS/2 for Windows" version 2.1, whose internal IBM codename was indeed "Ferengi".^[27] "Blue Spine" included Windows support in its own installation, and so could support Windows applications without a Windows installation. As most computers were sold with Microsoft Windows pre-installed, "Red Spine" was the far more popular product. OS/2 Warp Connect — which had full LAN client support built-in — followed in mid-1995. Warp Connect was nicknamed "Grape".^[6]

In OS/2 2.0, most performance-sensitive subsystems, including the graphics (Gre) and multimedia (MMPM/2) systems, were updated to 32-bit code in a fixpack, and included as part of OS/2 2.1. Warp 3 brought about a fully 32-bit Windowing system, while Warp 4 introduced the object-oriented 32-bit GRADD display driver model.

In 1996, Warp 4 added Java and speech recognition software. IBM also released server editions of Warp 3 and Warp 4 which bundled IBM's LAN Server product directly into the operating system installation. A personal version of Lotus Notes was also included, with a number of template databases for contact management, brainstorming, and so forth. The UK-distributed free demo CD-ROM of OS/2 Warp essentially contained the entire OS and was easily, even accidentally, cracked, meaning that even people who liked it did not have to buy it. This was seen as a backdoor tactic to increase the number of OS/2 users, in the belief that this would increase sales and demand for third-party applications, and thus strengthen OS/2's desktop numbers. This suggestion was bolstered by the fact that this demo version had replaced another which was not so easily cracked, but which had been released with trial versions of various applications. In 2000, the July edition of Australian Personal Computer magazine bundled software CD-ROMs, included a full version of Warp 4 that required no activation and was essentially a free release. Special versions of OS/2 2.11 and Warp 4 also included symmetric multiprocessing (SMP) support.

Workstation OS Plan to Replace OS/2

IBM also worked on a version of OS/2 for PowerPC to be sold as "Workstation OS". This was an entirely new product, not a port of the existing OS/2, that borrowed certain sections of code from both the existing OS/2 and AIX products while using an entirely new microkernel code base and adding major features including a system registry and a new driver model. IBM intended to replace the existing OS/2 with this more advanced version that would run exclusively on the PowerPC platform, forcing users to migrate to proprietary IBM hardware and eventually eliminating the Intel version. Advanced plans for the new code base included a vision of a replacement of the OS/400 operating system and a microkernel product that would have been used in industries such as telecommunications and set-top television receivers. A partial pre-alpha version of the client was demonstrated once at Comdex where a bemused Bill Gates stopped by the booth. However, a project was launched internally to evaluate the looming competitive situation with Microsoft Windows 95, the major code quality issues in the existing OS/2 product (resulting in over 20 service packs, each requiring more diskettes than the original installation), and the ineffective and heavily matrixed development organization in Boca Raton and Austin. That study revealed untenable weaknesses across the board in IBM and a decision was made to cut 95% of the overall budget for OS/2, eliminate the Boca Raton development laboratory, end all sales and marketing efforts of the product, and lay off over 1300 individuals. $900M USD had been spent in the last full year. Warp 4 became the last widely distributed version of OS/2.

Microsoft Windows NT provided server support for PowerPC — a chip co-developed and promoted by IBM — for over five years.

Fading out

Overall, OS/2 failed to catch on in the mass market and is little used outside certain niches where IBM traditionally had a stronghold. For example, many bank installations, especially Automated Teller Machines, run OS/2 with a customized user interface; French SNCF national railways used OS/2 1.x in thousands of ticket selling machines. Telecom companies such as Nortel use OS/2 in some voicemail systems. Also, OS/2 was used for the host PC used to control the Satellite Operations Support System equipment installed at NPR member stations from 1994 to 2007, and used to receive the network's programming via satellite. Nevertheless, OS/2 still maintains a small and dedicated community of followers.^[28]

Although IBM began indicating shortly after the release of Warp 4 that OS/2 would eventually be withdrawn, the company did not end support until December 31, 2006.^[29] Sales of OS/2 stopped on 2005-12-23. The latest IBM version is 4.52, which was released for both desktop and server systems in December 2001. Serenity Systems has been reselling OS/2 since 2001, calling it eComStation. Version 1.2 was released in 2004. After a series of preliminary "release candidates," version 2.0 GA (General Availability) was released on 15 May 2010.^[30] eComStation version 2.1 GA was released on May 20, 2011.^[31]

IBM is still delivering defect support for a fee.^[29][32] 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 migration to a different operating system, suggesting Linux as an alternative.^[33][34][35]

Virtualization

As of 2008^[update], support for running OS/2 under virtualization appears to be improving in a number of third-party products. OS/2 has historically been more difficult to run in a virtual machine than most other legacy x86 operating systems because of its extensive reliance on the full set of features of the x86 CPU.^[36]

During a pre-launch session (ESX3) with VMware in Oslo, Norway, December 2005, they specifically said that OS/2's use of the CPU's ring 2 was the reason that it would not run in VMware. A beta of VMWare Workstation 2.0 released in January 2000 was the first hypervisor that could run OS/2 at all. Later, the company decided to drop official OS/2 support.^[37] One can run OS/2 Warp 4 at Fixpack 5, but installing later Fixpacks will make the virtual machine unusable. eComStation 1.2 and 2.0 beta 4 will not install.^[38]

VirtualPC from Microsoft (originally Connectix) has been able to run OS/2 without hardware virtualization support for many years. It also provided “additions” code which greatly improves host-guest OS interactions in OS/2. The additions are not provided with the current version of VirtualPC, but the version last included with a release may still be used with current releases. At one point, OS/2 was a supported host for VirtualPC in addition to a guest. Note that OS/2 runs only as a guest on those versions of VirtualPC that use virtualization (x86 based hosts) and not those doing full emulation (VirtualPC for Mac).

VirtualBox from Oracle Corporation (originally InnoTek, later Sun) currently supports OS/2 Warp 3, 4 and 4.5 as well as eComStation as guests. However, attempting to run OS/2 and eComStation can still be difficult, if not impossible to run, because of the strict requirements of VT-x/AMD-V hardware-enabled virtualization and only ACP2/MCP2 is reported to work in a reliable manner.^[39]

QEMU and Bochs also support running OS/2 as they are full x86 system emulators and not virtualization software, and thus emulates the entire x86 architecture instead of relying on the host CPU, essentially allowing OS/2 unrestricted access to Ring 2, albeit an emulated one.

The difficulties in efficiently running OS/2 have, at least once, created an opportunity for a new virtualization company. A large bank in Moscow needed a way to use OS/2 on newer hardware that OS/2 did not support. As virtualization software is an easy way around this, the company desired to run OS/2 under a hypervisor. Once it was determined that VMware was not a possibility, it hired a group of Russian software developers to write a host-based hypervisor that would officially support OS/2. Thus, the Parallels, Inc. company and their Parallels Workstation was born.^[40]

ATMs

ATM vendors NCR Corporation and Diebold Incorporated have both adopted Microsoft Windows XP as their migration path from OS/2.

Diebold Incorporated initially shipped XP Embedded Edition exclusively, but following extensive pressure from customer banks to support a common OS, switched to XP Professional to match their primary competitor NCR Corporation.

Security niche

OS/2 has very few native computer viruses;^[41] while it is not invulnerable by design, its reduced market share appears to have discouraged virus writers. There are, however, OS/2-based antivirus programs, dealing with DOS viruses and Windows viruses that could pass through an OS/2 server.

Future

There is a community of OS/2 users and developers, along with loyal company customers, hoping that IBM will release OS/2 or a significant part of it as open source. These petitions were held in 2005 and 2007, but IBM refused these petitions, citing legal and technical reasons.^[42] It is unlikely that the entire OS will be open at some point in the future, because it contains third-party code, much of it from Microsoft.

In addition, IBM once made a deal with Commodore to license Amiga technology for OS/2 2.0 and above in exchange for the REXX scripting language.^[43] This means OS/2 may have code not written by IBM, which can prevent the OS from being open-sourced in the future.^[44][45] On the other hand IBM donated Object REXX for Windows and OS/2 to the Open Object REXX project maintained by the REXX Language Association on Sourceforge.^[46]

There is an ongoing petition to open parts of the OS arranged by OS2World.com.^[47]

Open source operating systems such as Linux have already profited from OS/2 indirectly through IBM's release of the improved JFS file system which was ported from the OS/2 code base. As IBM didn't release the source of the OS/2 JFS driver, developers ported the Linux driver back to eComStation and added the functionality to boot from a JFS partition. This new JFS driver has been integrated into eComStation v2.0, the successor of OS/2.

OSFree is an attempt to recreate the OS/2 Operating System (specifically OS/2 Warp 4) from scratch and licensed under the GNU GPL.^[48]

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 or the Windows GDI. On top of this lies the Workplace Shell (WPS) introduced in OS/2 2.0. WPS is an object-oriented shell allowing the user to perform traditional computing tasks such as accessing files, printers, launching legacy programs, and advanced object oriented tasks using built-in and third-party application objects that extended the shell in an integrated fashion not available on any other mainstream operating system. WPS follows IBM's Common User Access user interface standards.

Hardware vendors were reluctant to support device drivers for alternative operating systems including OS/2 and Linux, leaving users with few choices from a select few vendors. To relieve this issue for video cards, IBM licensed a reduced version of the Scitech display drivers, allowing users to choose from a wide selection of cards supported through Scitech's modular driver design.^[49]

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. The object oriented aspect of SOM is similar to, and a direct competitor to, Microsoft's Component Object Model, though it is implemented in a radically different manner; for instance, one of the most notable differences between SOM and COM is SOM's support for inheritance (one of the most fundamental concepts of OO programming) — COM does not have such support. SOM and DSOM are no longer being developed.

OS/2 also includes a radical advancement in application development with compound document technology called OpenDoc, which was developed with Apple. OpenDoc proved interesting as a technology, but was not widely used or accepted by users or developers. 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 support 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 as visible with SCCS what compatible tools.

Problems

Some problems were classic subjects of comparison with other operating systems:

• Synchronous input queue (SIQ): if a GUI application was not servicing its window messages, the entire GUI system could get stuck and a reboot was required. This problem was considerably reduced with later Warp 3 fixpacks and refined by Warp 4, by taking control over the application after it had not responded for several seconds.^[50]
• No unified object handles (OS/2 v2.11 and earlier): The availability of threads probably led system designers to overlook mechanisms which allow a single thread to wait for different types of asynchronous events at the same time, for example the keyboard and the mouse in a "console" program. Even though select was added later, it only worked on network sockets. In case of a console program, dedicating a separate thread for waiting on each source of events made it difficult to properly release all the input devices before starting other programs in the same "session". As a result, console programs usually polled the keyboard and the mouse alternately, which resulted in wasted CPU and a characteristic "jerky" reactivity to user input. In OS/2 3.0 IBM introduced a new call for this specific problem.^[51]

Historical uses

OS/2 is widely used in Iran Export Bank (Bank Saderat Iran) in their teller machines, ATMs and local servers (over 30,000 working stations). As of 2011, The bank moved to virtualize and renew their infrastructure by moving OS/2 to Virtual Machines running over Windows.

OS/2 was widely used in Brazilian banks. Banco do Brasil had a peak 10,000 machines running OS/2 Warp in the 1990s. OS/2 was used in automated teller machines until 2006. The workstations and automated teller machines and attendment computers have been migrated to Linux.^[52]

OS/2 is still used in the banking industry. Suncorp bank in Australia still ran its ATM network on OS/2 as late as 2002. ATMs in Perisher Blue used OS/2 as late as 2009, and even the turn of the decade.^[53]

OS/2 also was widely adopted by accounting professionals and auditing companies. In mid-1990s native 32-bit accounting software were well developed and serving corporate markets.

OS/2 ran the faulty baggage handling system and Denver's new airport to replace Stapleton. The OS was eventually scrapped, but led to massive delays in the opening of the new airport.

OS/2 was used by radio personality Howard Stern. He once had a 10 minute on-air rant about OS/2 versus Windows 95 and recommended OS/2. He also used OS/2 on his IBM 760CD laptop.

OS/2 is still used by Shell New Zealand Petroleum Stations as the main operating system.

OS/2 was used as part of the Satellite Operations Support System (SOSS) for NPR's Public Radio Satellite System. SOSS was a computer-controlled system using OS/2 that NPR member stations used to receive programming feeds via satellite. SOSS was introduced in 1994 using OS/2 3.0, and was retired in 2007, when NPR switched over to its successor, the ContentDepot.

OS/2 is still used to control the SkyTrain automated light rail system in Vancouver, Canada.

OS/2 was used in the London Underground Jubilee Line Extension Signals Control System (JLESCS) in London, UK. This control system delivered by Alcatel was in use from 1999 to 2011 i.e. between abandonment before opening of the line's unimplemented original automatic train control system and the present SelTrac system. JLESCS did not provide automatic train operation only manual train supervision. Six OS/2 local site computers were distributed along the railway between Stratford and Westminster, the shunting tower at Stratford depot, and several formed the central equipment located at Neasden. It was once intended to cover rest of the line between Green Park and Stanmore but this was never introduced.

OS/2 is still used by The Co-operative Bank in the UK for its domestic call centre staff, using a bespoke program created to access customer accounts which cannot easily be migrated to Windows.

OS/2 is still used by the Stop & Shop supermarket chain (and has been installed in new stores as recently as March 2010).

OS/2 is still used on ticket machines for Croydon Tramlink in outer-London (UK).

IBM Products that used OS/2

IBM used OS/2 in a wide variety of hardware products, effectively as a form of embedded operating system. Examples of products that used OS/2 include:

See also

• History of the graphical user interface
• Virtual DOS machine discusses the OS/2 VDM and seamless Win32s integration

References

Further reading

• Harvey M. Deitel and Michael S. Kogan (1992). The Design of OS/2. Addison Wesley. ISBN 0-201-54889-5. 
• Letwin, Gordon (1988). Inside OS/2. Microsoft Press. ISBN 1-55615-117-9. 
• Pascal, Zachary (1994). Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft.. Warner Books.. ISBN 0-02-935671-7. 
• Steve Wendt (missingdate). "OS/2 Warp history". missingwork. OS2BBS. http://www.os2bbs.com/os2news/OS2Warp.html. 
• Peter Moylan (2004-07-23). "Some fundamental OS/2 concepts". http://www.pmoylan.org/pages/os2/concepts.html. 
• Michal Necasek (2005-12-03). "OS/2 Warp, PowerPC Edition". The History of OS/2. http://pages.prodigy.net/michaln/history/os2ppc/index.html.  — Necasek discusses an aborted port to PowerPC machines.

External links

• os2world.com - Community of OS/2 users
• ecomstation.ru - Community of eComStation and OS/2 users
• netlabs.org - OpenSource Software for OS/2 and eCS
• OS/2 FAQ
• hobbes.nmsu.edu The OS/2 software repository
• eCSoft/2 - The OS/2 and eComstation software guide
• osFree an open source project to build an OS/2 clone operating system
• Voyager Project, to re implement OS/2 on modern technology
• OS/2 to Linux API porting project
• Open Source OS/2 API implementation for Windows
• Microsoft documentation of OS/2 API compatibility with Windows NT
• Technical details of OS/2
• The History of OS/2