OS/2 (Operating System/2) is a proprietary computer operating system for x86 and PowerPC based personal computers created and initially developed jointly by IBM and Microsoft, under the leadership of IBM software designer Ed Iacobucci, intended as a replacement for DOS. The first version was released in 1987. A feud between the two companies beginning in 1990 led to Microsoft's leaving development solely to IBM, which continued development on its own. OS/2 Warp 4 in 1996 was the last major upgrade, after which IBM slowly halted the product as it failed to compete against Microsoft's Windows; updated versions of OS/2 were released by IBM until 2001. 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 PCs. OS/2 was intended as a protected-mode successor of PC DOS targeting the Intel 80286 processor. Notably, basic system calls were modelled 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. Because of this heritage, OS/2 shares similarities with Unix, Xenix, and Windows NT. OS/2 sales were largely concentrated in networked computing used by corporate professionals. OS/2 2.0 was released in 1992 as the first 32-bit version as well as the first to be entirely developed by IBM, after Microsoft severed ties over a dispute over how to position OS/2 relative to Microsoft's new Windows 3.1 operating environment. With OS/2 Warp 3 in 1994, IBM attempted to also target home consumers through a multi-million dollar advertising campaign. Nonetheless, it continued to struggle in the marketplace, partly due to strategic business measures imposed by Microsoft in the industry that have been considered anti-competitive. Following the failure of IBM's Workplace OS project, OS/2 Warp 4 became the final major release in 1996; IBM discontinued its support for OS/2 on December 31, 2006. Since then, OS/2 has been developed, supported and sold by two different third-party vendors under license from IBM – first by Serenity Systems as eComStation from 2001 to 2011, and later by Arca Noae LLC as ArcaOS since 2017.
Development Ironically, Microsoft is competing against itself in the operating systems market. Besides Xenix, Microsoft has announced Windows 386, which [is] somewhat similar to OS/2. Of course, either way users turn, Microsoft wins.
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 don't need to 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)
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