OS/2

OS/2 is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci.

Architectural designer of the OS/2 and IBM DOS systems.

Since then, it has been updated, maintained and marketed under the name eComStation.

eComStation or eCS is a PC operating system based on OS/2, published by Serenity Systems and Mensys BV and currently owned and developed by XEU.com.

In 2015 it was announced that a new OEM distribution of OS/2 would be released that was to be called ArcaOS.

ArcaOS is an operating system developed and marketed by Arca Noae, LLC derived from OS/2, based on the last release by IBM.

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.

The OS/2 operating system was announced at the same time as the PS/2 line and was intended to be the primary operating system for models with Intel 80286 or later processors.

OS/2 is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. VirtualPC from Microsoft (originally Connectix) has been able to run OS/2 without hardware virtualization support for many years.

Despite having begun jointly developing a new operating system, OS/2, with IBM in August 1985, Microsoft released Microsoft Windows, a graphical extension for MS-DOS, on November 20.

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.

LAN Manager was based on the OS/2 operating system co-developed by IBM and Microsoft.

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.

The real-mode portion was meant to provide backward compatibility with existing operating systems such as DOS, and therefore was named "CBIOS" (for "Compatibility BIOS"), whereas the "ABIOS" (for "Advanced BIOS") provided new interfaces specifically suited for multitasking operating systems such as OS/2.

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).

Later, IBM brought DB2 to other platforms, including OS/2, UNIX, and MS Windows servers, and then Linux (including Linux on IBM Z) and PDAs.

Because of this heritage, OS/2 shares similarities with Unix, Xenix, and Windows NT.

However, the project was originally intended as a follow-on to OS/2 and was referred to as "NT OS/2" before receiving the Windows brand.

In 1989, Version 1.2 introduced Installable Filesystems and, notably, the HPFS filesystem.

HPFS (High Performance File System) is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system.

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.

For example, OS/2, GNU/Linux, FreeBSD and BeOS provide built-in support for FAT, even though they also support more sophisticated file systems such as ext4 or btrfs.

The promised user interface, Presentation Manager, was introduced with OS/2 1.1 in October 1988.

Presentation Manager (PM) is the graphical user interface (GUI) that IBM and Microsoft introduced in version 1.1 of their operating system OS/2 in late 1988.

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.

In computing, Dynamic Data Exchange (DDE) is a technology for interprocess communication used in early versions of Microsoft Windows or OS/2.

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".

The use of expanded memory became common with games and business programs such as Lotus 1-2-3 in the late 1980s through the mid-1990s, but its use declined as users switched from DOS to protected-mode operating systems such as Linux, IBM OS/2, and Microsoft Windows.

It also included a new OOUI (object-oriented user interface) called the Workplace Shell.

The Workplace Shell (WPS) is an object-oriented desktop shell (also called Desktop Environment) produced by IBM's Boca Raton development lab for OS/2 2.0.

OS/2 was intended as a protected-mode successor of PC DOS.

On April 2, 1987 OS/2 was announced as the first product produced under the agreement.

OS/2 is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci.

There have been many operating systems that were significant in their day but are no longer so, such as AmigaOS; OS/2 from IBM and Microsoft; classic Mac OS, the non-Unix precursor to Apple's macOS; BeOS; XTS-300; RISC OS; MorphOS; Haiku; BareMetal and FreeMint.

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.

The company made versions of its office suite for IBM OS/2 and Microsoft Windows.

Because of this heritage, OS/2 shares similarities with Unix, Xenix, and Windows NT.

It agreed with IBM to develop OS/2, and the XENIX team (together with the best MS-DOS developers) was assigned to that project.

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.

Microsoft and IBM together began what was intended as the follow-on to MS-DOS/PC DOS, called OS/2.

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.

Simultaneously with Windows 3.1's release, IBM started shipping OS/2 2.0.

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.

APPC is mainly used by IBM installations running operating systems such z/OS (formerly MVS then OS/390), z/VM (formerly VM/CMS), z/TPF, IBM i (formerly OS/400), OS/2, AIX and z/VSE (formerly DOS/VSE).

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.

IBM Works is an office suite for the IBM OS/2 operating system.

VirtualPC from Microsoft (originally Connectix) has been able to run OS/2 without hardware virtualization support for many years.

Connectix sold versions of Virtual PC bundled with a variety of guest operating systems, including Windows, OS/2, and Red Hat Linux.

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.

Workplace OS featured a new port of OS/2 (with Intel emulation for application compatibility), pending a successful launch of the PowerPC 620.