OS/2 was meant as a protected mode successor of MS-DOS and Microsoft Windows. Notably, basic system calls were modeled after MS-DOS calls; their list possibly began using "Dos" & it was conceivable to hyperlink text mode applications in such how else that it may operate in each systems ("bound" software download). Because of this heritage, inside terms of look, sense & features, OS/2 is non unlike Windows inside numbers of ways; however it likewise shares similarities by owning Unix and XENIX.

Development history

Enthusiastic beginnings

IBM & Microsoft signed a Joint Development Agreement inside August 1985.

OS/2 One.Cipher was announced around April 1987 and released inside December, as a text mode-only OS. It still featured the rich API for controlling the video display (VIO) and receiving keyboard and mouse events, the rather the protected-mode BIOS. Non amazingly, a streaming video & keyboard APIs were besides available to "bound" software online in MS-DOS. A promised GUI, Presentation Manager, was introduced by using OS/2 One.Ace within November 1988. Version One.Two introduced a HPFS filesystem.

OS/2 & Windows-related books of the late 1980s acknowledged a being of two systems & promoted OS/2 when the models for the new.

Breakup

A collaboration between IBM & Microsoft unravelled within 1990, between the releases of Windows 3.0 and OS/2 1.3. At first, at least publicly, Microsoft continued to insist a new belonged to OS/2. Steve Ballmer of Microsoft even took to calling OS/2 "Windows Plus". It was a public, nevertheless, that chose Windows all over OS/2. A increasing popularity of Windows prompted Microsoft to shift its development focus from either OS/Two, & IBM grew caring all about delays inside development of OS/2 2.Cypher. Ab initio, a corporations agreed that IBM would choose across maintenance of OS/2 One.Zero & development of OS/Two 2.Cipher, when Microsoft would prove my point development of OS/2 Three.Nought, so called "NT OS/2", which purportedly stood for Future Technology. Yet, Microsoft decided to recast NT OS/2 when Windows NT, leaving completely first OS/2 development to IBM. Windows NT's OS/2 heritage may be seen within its initial trend lines for the HPFS filesystem (although write support was drop by Windows NT Four.Zero & scan trend lines was drop by Windows 2000) and text mode OS/2 One.10 applications (trend lines come by Windows XP).

Competition with Windows

OS/Two 2.Zero, freed around 1992, was touted by IBM as "a better DOS than DOS and a better Windows than Windows". Indeed, because of the limitations of the Intel 80286 processor, OS/2 1.x may merely start a single "DOS box" at one time, & did this around an unsafe way by ping-ponging a entire processor between very & secure modes, using the undocumented LOADALL machine instruction. a condition inside DOS mode would crash the entire computer. Within direct contrast, OS/Two 2.Cypher can profit from either a virtual 8086 mode of the Intel 80386 processor in order to produce the possibly whole assure virtual machine for DOS to run in. All a same, such the locate VM incurs the important performance hit in comparison original devices, & unsecuring a bit of vicinity of the VM (OS/2 was super configurable in that area) to produce it further usable once again allowed DOS software download to crash the computer. Good such as Windows, OS/2 may not redo secure mode DOS software online using the older VCPI interface; it only supported software download written based on data from DPMI.

Compatibility by owning Windows was achieved by adapting Windows GUI code to process in the 16-bit OS/2 process, like than above a original Windows kernel. For this cause, Windows may not do in the therefore-supposed "386 enhanced" mode (which did non matter a lot, since OS/2 managed virtual memory & DOS virtual machines independently). Originally, Windows code was involved in the distribution, however afterwards red OS/2 versions reused whatever Windows version a user experienced installed antecedently, patching it on the fly.

This rerun containing Windows may either run good-screen, applying its have placed of cd drivers, or even "seamlessly", in which Windows software would pop up directly on the OS/2 desktop. Once more, this expected specially enabled drivers. To achieve isolation between Windows software online, OS/2 required to start many copies of Windows around parallel. This approach provided unfortunate stability. E.g., shift between a OS/2 desktop & a Windows desktop may well hang a machine & compulsory considerable body resources, especially memory. Microsoft utilized the simpler approach inside Windows NT, translating Win16 supervisor call instruction to Win32 ones by the means of the Windows-on-Windows adaptation layer.

OS/Two 2.Cipher too provided a fresh GUI known as the Workplace Shell & the 32-bit API for indigen software, though a OS itself wwhen a mixture of Sixteen-bit and 32-bit code (as Windows 95 would be).

OS/2 Warp Three, freed inside 1994, was a fully 32-bit OS. It offered the unsuspecting hosts of advantages, notably wide devices trend lines, greater multimedia system capabilities, Internet-compatible networking, and the basic professional application suite. Within 1996, Warp 4 added Java and voice recognition software. IBM likewise freed server editions of Warp Three & Warp Four. A UK-distributed loose demonstration CD-ROM of OS/2 Warp essentially contained a entire OS & was easy, potentially inadvertently, cracked, meaning that possibly humans world health organization liked it didn't use at times to pip out.

Fading out
Overall, OS/2 failed to catch in in the mass market & is in todays world little utilized outside certain niches in which IBM traditionally got the fastness. E.g., several banks, especially Automated Teller Machines, run OS/2 by using the custom interface; French SNCF national railways used OS/2 One.x within hundreds to thousands of ticket selling machines. however, OS/2 still maintains the microscopic & dedicated community of followers. IBM, unlike Microsoft, charged ISVs for a OS/2 development kit, while Microsoft gave the Windows SDK away free.

Although IBM began indicating shortly when the release of Warp Four that OS/2 would in time exist as withdrawn, a company has exclusively recently published a definite prevent-of-trend lines date (December 31 2006). Gross revenue of OS/2 might prevent in December 23 2005. A latest IBM version is Quaternion.52, which was freed for two desktop & server systems around December 2001. The company known as Serenity Systems has been reselling OS/2 since 2001, calling it eComStation. A latest version is I.Deuce, freed inside 2004.

IBM is however redeeming fixes & updates regularly. IBM urges client to migrate their typically extremely complex applications to e-business technologies such as Java in a platform-neutral manner. Another time application migration is completed, IBM recommends to migrate to the different operating patterns suggesting consideration of Linux as an alternative.

One of a reasons how come OS/2 can be doomed to a higher degree more bequest x86 operating systems is its extensive reliance on the full placed of features of this architecture. the symptom is that these are impossible to do OS/2 in a VMware virtual machine. Although the beta of VMWare Two.Cypher was freed a couple of years ago which may start OS/2 the least bit, it get it on super slowly. Late, a company decided to explicitly drop OS/2 trend lines, presumptively because it would call for good & non economically justified sweetening.

Ironically, Microsoft continues to support OS/2 as a hosted operating system in its Virtual PC product. Presumptively this trend lines is present to encourage OS/2 users to migrate to the Windows server based platform.

Security niche

OS/2 is virtually unhampered computer viruses. Its project even stand processed it when vulnerable when Windows, however its decreased market part appears to use discouraged virus writers. There are, even so, OS/2-depending antivirus software, treating sustaining DOS viruses & Windows viruses that may pass across an OS/2 server.

Future
There is the community of OS/2 users & developers, along by owning truehearted company client, hoping that IBM might release OS/2 or even a important a portion of it when open source. These are unconvincing, though, that a entire OS is open because it contains third-person code, very much of it from either Microsoft.

Indeed, although a 32-bit version of OS/2 is typically believed to become IBM's have function, the beta version of 2.Cipher, accompanied by an SDK, was actually released by Microsoft in the 2nd half of 1990 already. OS/2 32-bit workable files keep close at hand virtually exactly a equivalent format when Windows 3.0 VxD device drivers, older 16-bit executables have the format of Windows executables, etc. This suggests that a project & disregard was however treat Microsoft. IBM's contribution mostly lives in a GUI components (notably, IBM has caused the revamping of the Windows interface based on data from Systems Application Architecture standards after a signature of a JDA, between the release of One.x & Ii.10 versions; late a few of the crucial population from either their team split away to form Citrix). A aborted PowerPC port however did non require Microsoft, & hwhen been proposed as a basis for an open-source 64-bit version of OS/2.

However, a community has suggested that, potentially if only a IBM portion of it is mass produced open, the missing area can be written per equivalent community to form a next-generation version of the OS. There exists an on-going petition to open area of the OS. See [http://www.os2world.com/petition/ Petition to open]

By having the possibility of an open-source fresh for OS/2, a OS can be given a new lease of life. IBM's todays & heavily involvement using many open source projects suggest that opening area of OS/2 may non exist as hard for the company. However until so, OS/2's new remains inside limbo.

Open source operating systems like Linux have already profited from OS/2 indirectly across IBM's release of the improved JFS file system which was ported from a OS/2 code base.

Technology
the graphic technique has a layer known as Presentation Manager that manages windows, fonts, and icons. This is similar around functionality to the non-networked version of X11. In top of this lies a Workplace Shell (WPS), introduced in OS/Two 2.Cypher, which is an object-oriented shell allowing the user to access files & printers, & launch software download. WPS follows IBM's Common User Access user interface standards.

Within recent years, IBM decided does'nt to trend lines the superfluity of graphic cards, & licensed a decreased version of Scitech drivers.

WPS is objects like disks, folders, files, program objects, & printers using the System Object Model (SOM), which allows code to be shared among applications, even written within different programing language. The distributed versiin known as DSOM allowed objects on different computers to communicate. DSOM is according to CORBA. SOM is similar to, & the directly challenger to, Microsoft's Component Object Model. SOM & DSOM come there is no hanker existence developed.

OS/2 too includes the compound document technology known as OpenDoc, which was developed with Apple. OpenDoc is likewise there is no hanker existence developed.

A multimedia system capabilities of OS/2 come accessible across Media Control Interface commands. A previous upgrade (bundled sustaining a IBM version of Netscape Navigator plugins) added support for MPEG files. Trend lines for fresh formats rather PNG, progressive JPEG, DivX, OGG, MP3 comes from third parties. Occasionally these are integrated by having a multimedia, however inside more offers it comes when standalone applications.

A TCP/IP stack is based on a open source BSD stack.

Quotes
In a period of the next Tenner years, hundreds to thousands of coder & users might use this body Bill Gates, November 1988 (in the Foreword to the In OS/2 book by Gordon Letwin, Microsoft's architect for OS/2).

This quote may be interestingly equated sustaining some other a single, by Dave Cutler and coming from his introduction to the In Windows NT book: ''In the summertime of 1988, We received an interesting call for from either Bill Gates at Microsoft. He asked whether I personally'd rather to came all over & talk all about building the recently operating formulas at Microsoft for pc. [...] What Bill got to offer was a chance to build a second operating rules, 1 that was personal [...]''.