Open systems are

computer system A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...

s that provide some combination of

interoperability Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader defi ...

, portability, and open software standards. (It can also refer to specific installations that are configured to allow unrestricted access by people and/or other computers; this article does not discuss that meaning). The term was popularized in the early 1980s, mainly to describe systems based on

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...

, especially in contrast to the more entrenched mainframes and

minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ' ...

s in use at that time. Unlike older

legacy system In computing, a legacy system is an old method, technology, computer system, or application program, "of, relating to, or being a previous or outdated computer system", yet still in use. Often referencing a system as "legacy" means that it pave ...

s, the newer generation of Unix systems featured standardized programming interfaces and peripheral interconnects; third party development of hardware and software was encouraged, a significant departure from the norm of the time, which saw companies such as

Amdahl Amdahl may refer to: People * Einar Amdahl (1888-1974), Norwegian theologist * Bjarne Amdahl (1903-1968), Norwegian pianist and composer * Douglas K. Amdahl (1919–2010), American lawyer and judge from Minnesota * Gene Amdahl (1922–2015), for ...

and

Hitachi () is a Japanese multinational conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Nissan ''zaibatsu'' and later DKB Group and Fuyo G ...

going to court for the right to sell systems and peripherals that were compatible with IBM's mainframes. The definition of "open system" can be said to have become more formalized in the 1990s with the emergence of independently administered software standards such as

The Open Group The Open Group is a global consortium that seeks to "enable the achievement of business objectives" by developing "open, vendor-neutral technology standards and certifications." It has over 840 member organizations and provides a number of servi ...

's Single UNIX Specification. Although computer users today are used to a high degree of both hardware and software interoperability, in the 20th century the open systems concept could be promoted by Unix vendors as a significant differentiator. IBM and other companies resisted the trend for decades, exemplified by a now-famous warning in 1991 by an IBM account executive that one should be "careful about getting locked into open systems". However, in the first part of the 21st century many of these same legacy system vendors, particularly IBM and

Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

, began to adopt

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

as part of their overall sales strategy, with "

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized so ...

" marketed as trumping "open system". Consequently, an IBM mainframe with

Linux on IBM Z Linux on IBM Z or Linux on zSystems is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z / IBM zSystems and IBM LinuxONE servers. Similar terms which imply the same meaning are ''Linux/390'', ...

is marketed as being more of an open system than commodity computers using closed-source

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

—or even those using Unix, despite its open systems heritage. In response, more companies are opening the source code to their products, with a notable example being

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, t ...

and their creation of the

OpenOffice.org OpenOffice.org (OOo), commonly known as OpenOffice, is a discontinued open-source office suite. Active successor projects include LibreOffice (the most actively developed), Apache OpenOffice, Collabora Online (enterprise ready LibreOffice) a ...

and

OpenSolaris OpenSolaris () is a discontinued open-source computer operating system based on Solaris and created by Sun Microsystems. It was also, perhaps confusingly, the name of a project initiated by Sun to build a developer and user community around t ...

projects, based on their formerly closed-source

StarOffice StarOffice is a discontinued proprietary office suite, intended to compete with the marketing-leading Microsoft Office. It served as the basis for open-source suites OpenOffice.org and LibreOffice. StarOffice supported the OpenOffice.org XML f ...

and Solaris software products.

References

{{Reflist Computer systems History of computing Unix history

See also

References