1985–1990: Joint IBM–Microsoft development The development of OS/2 began when IBM and Microsoft signed the "Joint Development Agreement" in August 1985. It was code-named "CP/DOS" and it took two years for the first product to be delivered.
OS/2 1.0 (1987) OS/2's release was long delayed. It was widely believed that all IBM programmers used
assembly language, and a rumour said that the delay was because they had to learn the programming language
C. OS/2 1.0 was announced in April 1987 and released in December. The original release only ran in
text mode, and a GUI was introduced with OS/2 1.1 about a year later. OS/2 features an
API for controlling the
video display (VIO) and handling
keyboard and mouse events so that programmers writing for
protected mode need not call the
BIOS or access hardware directly. Other development tools included a subset of the video and keyboard APIs as linkable libraries so that family mode programs are able to run under MS-DOS, and, in the OS/2 Extended Edition v1.0, a database engine called Database Manager or DBM (this was related to
DB2, and should not be confused with the
DBM family of database engines for Unix and
Unix-like operating systems). 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 can run multiple programs). 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. Microsoft's
Bill Gates predicted at a 1987
Computerworld interview that "three years out, over 80% of new office systems will be based on OS/2".
Ashton-Tate's
Ed Esber also predicted success, while
Lotus Development's
Jim Manzi said "I don't know anyone who's screaming for OS/2. End users would really prefer that the whole thing never happened". Gates said that Microsoft would release Windows software first with "very cheap upgrades" to OS/2 versions, while the other two said their companies would release for OS/2 first.
OS/2 1.1 (1988) The promised user interface,
Presentation Manager, was introduced with OS/2 1.1 in October 1988. It had a similar user interface to
Windows 2.1, which was released in May of that year. (The interface was replaced in versions 1.2 and 1.3 by a look closer in appearance to
Windows 3.0.) 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.
OS/2 1.2 (1989) In 1989, Version 1.2 introduced Installable Filesystems and, notably, the
HPFS filesystem. HPFS provided a number of improvements over the older
FAT file system, including long filenames and a form of
alternate data streams called
Extended Attributes. In addition, extended attributes were also added to the FAT file system. The Extended Edition of 1.2 introduced
TCP/IP and
Ethernet support. OS/2- and Windows-related books of the late 1980s from both Microsoft's
Gordon Letwin and his IBM counterpart
Ed Iacobucci acknowledged the existence of both systems and promoted OS/2 as the system of the future.
1990: Breakup OS/2 1.3 (1990) 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. Much of its success was because Windows 3.0 (along with MS-DOS) was bundled with most new computers. OS/2, on the other hand, was available only as an additional stand-alone software package. In addition, OS/2 lacked
device drivers for many common devices such as printers, particularly non-IBM hardware. 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 its own business based on Windows. Several technical and practical reasons contributed to this breakup. The two companies had significant 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, and urged Microsoft to drop features, such as
fonts, that IBM's hardware did not support. Microsoft programmers also became frustrated with IBM's bureaucracy and its use of
lines of code to measure
programmer productivity. IBM developers complained about the terseness and lack of
comments in Microsoft's code, while Microsoft developers complained that IBM's code was
bloated. The two products have significant 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. 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. OS/2 1.x targets the
Intel 80286 processor and DOS fundamentally does not. IBM insisted on supporting the 80286 processor, with its 16-bit
segmented memory mode, because of commitments made to customers who had purchased many 80286-based PS/2s as a result of IBM's promises surrounding OS/2. 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 "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
VAX/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 on the
MICA project at
Digital rather than creating a "DOS plus". His
NT OS/2 was a completely new architecture. IBM grew concerned about the 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. 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 it waited 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. Windows NT could also support OS/2 1.x
Presentation Manager and AVIO applications with the addition of the Windows NT Add-On Subsystem for Presentation Manager.
1990–1996: Post-breakup OS/2 2.0 (1992) OS/2 2.0 was released in April 1992. At the time, the suggested retail price was , while Windows retailed for . OS/2 2.0 provided a 32-bit API for native programs, though the OS itself still contained some 16-bit code and drivers. It also included a new OOUI (object-oriented user interface) called the
Workplace Shell. This was a fully object-oriented interface 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 the user could manage programs, files and devices by manipulating objects on the screen. With the Workplace Shell, everything in the system is an "object" to be manipulated. OS/2 2.0 was touted by IBM as "a better DOS than DOS and a better Windows than Windows". It managed this by including the fully-licensed MS-DOS 5.0, which had been patched and improved upon. 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 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 leverage the
virtual 8086 mode of the
Intel 80386 processor 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 8086
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 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.) Unlike Windows NT, OS/2 always allowed DOS programs the possibility of masking real hardware interrupts, so any DOS program could
deadlock the machine in 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 80486 and
Intel Pentium processors—the
Virtual Interrupt Flag (VIF), which was part of the
Virtual Mode Extensions (VME)—to solve this problem. To accommodate those who wanted to have multiple operating systems on their machine, Boot Manager was introduced that allowed for the creation of separate partitions on the boot drive which could be used to install different versions of DOS, Windows and OS/2 and give the user a choice of which partition to boot from.
OS/2 2.1 (1993) OS/2 2.1 was released in 1993. This version of OS/2 achieved compatibility with Windows 3.0 (and later Windows 3.1) by adapting Windows user-mode code components to run inside a
virtual DOS machine (VDM). 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. 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. Because OS/2 only runs the user-mode system components of Windows, it is incompatible with Windows device drivers (
VxDs) and applications that require them. Multiple Windows applications run by default in a single Windows session – multitasking cooperatively and without memory protection – just as they would under native Windows 3.x. However, to achieve true isolation between Windows 3.x programs, OS/2 can also run multiple copies of Windows in parallel, with each copy residing in a separate VDM. The user can then optionally place each program either in its own Windows session – with preemptive multitasking and full memory protection
between sessions, though not
within them – or allow some applications to run together cooperatively in a shared Windows session while isolating other applications in one or more separate Windows sessions. At the cost of additional hardware resources, this approach can protect each program in any given Windows session (and each instance of Windows itself) from every other program running in any
separate Windows session (though not from other programs running in the same Windows session). Whether Windows applications are running in full-screen or windowed mode, and in one Windows session or several, it is possible to use
DDE between OS/2 and Windows applications, and
OLE between Windows applications only. IBM's
OS/2 for Windows product (codename Ferengi), also known as "OS/2, Special Edition", was interpreted as a deliberate strategy "of cashing in on the pervasive success of the Microsoft platform" but risked confusing consumers with the notion that the product was a mere accessory or utility running on Windows such as
Norton Desktop for Windows when, in fact, it was "a complete, modern, multi-tasking, pre-emptive operating system", itself hosting Windows instead of running on it. Available on CD-ROM or 18 floppy disks, the product documentation reportedly suggested Windows as a prerequisite for installing the product, also being confined to its original FAT partition, whereas the product apparently supported the later installation of Windows running from an HPFS partition, particularly beneficial for users of larger hard drives. Windows compatibility, relying on patching specific memory locations, was reportedly broken by the release of Windows 3.11, prompting accusations of arbitrary changes to Windows in order to perpetrate "a deliberate act of Microsoft sabotage" against IBM's product. of the then-upcoming series
Star Trek: Voyager substituted for him at the last minute. OS/2 Warp offers a host of benefits over OS/2 2.1, notably broader hardware support, greater multimedia capabilities,
Internet-compatible networking, and it includes 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 utilizing any existing installation of Windows on the computer's hard drive. "Blue Spine" includes Windows support in its own installation, and so can support Windows applications without a Windows installation. As most computers were sold with Microsoft Windows pre-installed and the price was less, "Red Spine" was the more popular product. OS/2 Warp Connect—which has full LAN client support built-in—followed in mid-1995. Warp Connect was nicknamed "Grape". Workplace OS was developed solely for
POWER platforms, and IBM intended to market a full line of PowerPCs in an effort to take over the market from
Intel. A mission was formed to create prototypes of these machines and they were disclosed to several corporate customers, all of whom raised issues with the idea of dropping Intel. Advanced plans for the new code base would eventually include replacement of the
OS/400 operating system by Workplace OS, as well as a microkernel product that would have been used in industries such as telecommunications and set-top television receivers. A partially functional pre-alpha version of Workplace OS was demonstrated at Comdex, where a bemused
Bill Gates stopped by the booth. The second and last time it would be shown in public was at an OS/2 user group in
Phoenix, Arizona; the pre-alpha code refused to boot. It was released in 1995. But with $990 million being spent per year on development of this as well as Workplace OS, and no possible profit or widespread adoption, the end of the entire Workplace OS and OS/2 product line was near.
OS/2 Warp 4 (1996) 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. OS/2 sales were largely concentrated in networked computing used by corporate professionals; however, by the early 1990s, it was overtaken by Microsoft Windows NT. While OS/2 was arguably technically superior to Microsoft
Windows 95, OS/2 failed to develop much penetration in the consumer and stand-alone desktop PC segments; there were reports that it could not be installed properly on IBM's own
Aptiva series of home PCs. Microsoft made an offer in 1994 where IBM would receive the same terms as
Compaq (the largest PC manufacturer at the time) for a license of Windows 95, if IBM ended development of OS/2 completely. IBM refused and instead went with an "IBM First" strategy of promoting OS/2 Warp and disparaging Windows, as IBM aimed to drive sales of its own software as well as hardware. By 1995, Windows 95 negotiations between IBM and Microsoft, which were already difficult, stalled when IBM purchased
Lotus SmartSuite, which would have directly competed with
Microsoft Office. As a result of the dispute, IBM signed the license agreement 15 minutes before Microsoft's Windows 95 launch event, which was later than their competitors and this badly hurt sales of IBM PCs. IBM officials later conceded that OS/2 would not have been a viable operating system to keep them in the PC business.
1996–2001: Downsizing A project was launched internally by IBM to evaluate the looming competitive situation with Microsoft Windows 95. Primary concerns included 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 (where the consultants reported that "basically, everybody reports to everybody") and Austin. That study, tightly classified as "Registered Confidential" and printed only in numbered copies, identified untenable weaknesses and failures across the board in the Personal Systems Division as well as across IBM as a whole. This resulted in a decision being made at a level above the Division to cut over 95% of the overall budget for the entire product line, end all new development (including Workplace OS), eliminate the Boca Raton development lab, end all sales and marketing efforts of the product, and lay off over 1,300 development individuals (as well as sales and support personnel). $990 million had been spent in the last full year. Warp 4 became the last distributed version of OS/2.
2001–2006: Discontinuation and end-of-life Although a small and dedicated community remains faithful to OS/2, 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. Telecom companies such as
Nortel used 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. 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, with sales of OS/2 stopping on December 23, 2005. The latest IBM OS/2 Warp version is 4.52, which was released for both desktop and server systems in December 2001. IBM is still delivering defect support for a fee. 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.
2001–present: Third-party development After IBM discontinued development of OS/2, various third parties approached IBM to take over future development of the operating system. The OS/2 software vendor
Stardock made such a proposal to IBM in 1999, but it was not followed through by the company. Serenity Systems succeeded in negotiating an agreement with IBM, and began reselling OS/2 as eComStation in 2001. eComStation is now sold by XEU.com, the most recent version (2.1) was released in 2011. In 2015, Arca Noae, LLC announced that they had secured an agreement with IBM to resell OS/2.
Petitions for open source Many people hoped that IBM would release OS/2 or a significant part of it as
open source. Petitions were held in 2005 and 2007, but IBM refused them, citing legal and technical reasons. It is unlikely that the entire OS will be open at any point in the future because it contains third-party code to which IBM does not have copyright, and much of this code is from Microsoft. IBM also once engaged in a technology transfer with
Commodore, licensing
Amiga technology for OS/2 2.0 and above, in exchange for the
REXX scripting language. This means that OS/2 may have some code that was not written by IBM, which can therefore prevent the OS from being re-announced as open-sourced in the future. 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. There was a petition, arranged by OS2World, to open parts of the OS. 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, and later into ArcaOS 5.0. ==Summary of releases==