Sun - Operating systems

Sun is most well known for its Unix systems, which have a reputation for system stability and a consistent design philosophy.
Sun's first workstation shipped with UniSoft V7 Unix. Later in 1982 Sun began providing SunOS, a customized 4.1BSD Unix, as the operating system for its workstations.
In the late 1980s, AT&T tapped Sun to help them develop the next release of their branded UNIX, and in 1988 announced they would purchase up to a 20% stake in Sun. UNIX System V Release 4 (SVR4) was jointly developed by AT&T and Sun; this partnership triggered concern among Sun's competitors, many of whom banded together to form the Open Software Foundation (OSF). By the mid-1990s, the ensuing Unix wars had largely subsided, AT&T had sold off their Unix interests, and the relationship between the two companies was significantly reduced.
Sun used SVR4 as the foundation for Solaris 2, which became the successor to SunOS.
From 1992 Sun also sold INTERACTIVE UNIX, an operating system it acquired when it bought INTERACTIVE Systems Corporation from Eastman Kodak Company. This was a popular UNIX variant for the PC platform and a major competitor to market leader SCO UNIX. Sun's focus on INTERACTIVE UNIX diminished in favor of Solaris on both SPARC and x86 systems; it was dropped as a product in 2001.[citation needed]
In the past, Sun has offered a separate variant of Solaris called Trusted Solaris, which included augmented security features such as multilevel security and a least privilege access model. Solaris 10 included many of the same capabilities as Trusted Solaris when it was released in 2005; the Solaris 10 11/06 update included Solaris Trusted Extensions, which give it the remaining capabilities needed to make it the functional successor to Trusted Solaris.
Following several years of difficult competition and loss of server market share to competitors' Linux-based systems, Sun began to include Linux as part of its strategy in 2002. Sun supports both Red Hat Enterprise Linux and SUSE Linux Enterprise Server on its x64 systems; companies such as Canonical Ltd., Wind River Systems and MontaVista also support their versions of Linux on Sun's SPARC-based systems.
In 2004, Sun surprised the industry when, after having cultivated a reputation as one of Microsoft's most vocal antagonists, it entered into a joint relationship with them, resolving various legal entanglements between the two companies and receiving a US$1 billion settlement payment from them. Sun now supports Microsoft Windows on its x64 systems, and has announced other collaborative agreements with Microsoft, including plans to support each others' virtualization environments.