The Journal of Open Computing
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à Welcome from the Editor
à Open Source Groundswell
à Jon Hall on Standards
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à The Productivity Underground
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à The Open Group: Clustering
à The Open Group: Why Unix?
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White Paper

The UNIXâ Operating System:

Mature, Standardized and State-of-the-Art

The UNIXâ Operating System Environments:
Mature, Standardized, Branded, and State-of-the-Art

Executive Summary

Is it possible for an Information Technology [IT] product to be both mature and state-of-the-art at the same time? In the case of the UNIXâ system, the answer is an unqualified "Yes." The UNIX systems hasve continued to develop nonstop over the past twenty-five years. In millions of installations running on nearly every hardware platform made, the UNIX system has earned its reputation for stability and scalability. Over the years, UNIX system suppliers have steadily assimilated new technologies so that UNIX systems today provide as much or more functionality as any other operating system.

Perhaps the key to the continuing growth of the UNIX system is the free-market demands placed upon suppliers who produce and support software built to open public standards. The "open systems" approach is in bold contrast to other operating environments that lock in their customers with resultant high switching costs. UNIX system suppliers, on the other hand, must constantly provide the highest quality systems in order to retain their customers. Those who become dissatisfied with one UNIX system implementation retain the ability to easily move to another UNIX system implementation.

The continuing success of the UNIX system should come as no surprise. No other operating environment enjoys the support of every major system supplier. Mention the name UNIX system and IT professionals immediately think not only of the operating system itself, but also of the large family of hardware and application software that the UNIX system supports. In the IT marketplace, the UNIX system has been the catalyst for sweeping changes that have empowered consumers to seek the best-of-breed without the arbitrary constraints imposed by proprietary environments.

In a nutshell, then, the UNIX system is the users’ and suppliers’ operating environment of choice. The UNIX system represents the best collective efforts of competing suppliers, the most refined standards in the public domain, and the rock-solid stability that comes from years of quality assurance testing, mission-critical use, and refinement.

This white paper examines the UNIX system with a special concern for both its extraordinary past and its equally extraordinary prospects for the future.

The UNIX System

When the UNIX system was invented in 1969, it was solely designed to be useful. It grew from academic roots and was enthusiastically adopted in academic and research communities around the world. A survey conducted by the Computer Science Research Network (CSNET) found that, by 1980, over 90 percent of all departments in academic institutions were served by at least one UNIX system.

The UNIX system has been around for a long time, and many people may remember it as it existed in the previous decades. Many IT professionals who encountered UNIX systems in the past found it uncompromisingintimidating. While its power was impressive, its command-line interface required technical competence, its syntax was not intuitive, and its interface was unnot friendly.

Moreover, in the UNIX system’s early days, security was virtually nonexistent. Subsequently, the UNIX system became the first operating system to suffer attacks mounted over the nascent international Internet. As the UNIX system matured, however, the organization fundamental architecture of security shifted from centralized to distributed authentication and authorization systems.

Today, these perceptions are only of historical interest.

Now, a single Graphical User Interface is shipped and supported by all major vendors has replaced command-line syntax, and security systems, up to and including B1, provide appropriate controls over access to the UNIX systems.

The Value of Standards

The UNIX system’s increasing popularity spawned the development of a number of variations of the UNIX operating system in the 1980s, and the existence of these of many UNIX system brands caused a mid-life crisis for the UNIX system itself in the 1980s. Standardization had progressed slowly and methodically in domains such as telecommunications and software’s third-generation languages.; Yyet, no one had addressed cross-vendor standards at the operating system level. For suppliers, the thought of a uniform operating environment was disconcerting. Consumer lock-in was woven tightly into the fabric of the industry. Individual consumers, particularly those with UNIX system experience, envisioned standardized environments, but had no way to pull the market in their direction.

However, for one category of consumer —governments— the standardization of the UNIX system was both desirable and within reach. Governments have clout and are the largest consumers of information technology products and services in the world. Driven by the need to improve commonalitycross-vendor interoperations, both US and European governments endorsed a shift to the UNIX systems. The Institute of Electrical and Electronic Engineers POSIX family of standards, along with standards from ISO, ANSI and others, led the way. Consortia such as the Open Software Foundation and X/Open Company (merged with the Open Software Foundation in in 1995 to form the Open Group) hammered out draft standards to accelerate the process and developed test suites to certify open products.

In 1994, the definitive specification of what constitutes a UNIX system was finalized through X/Open Company’s consensus process. The Single UNIX Specification was born—not from a theoretical, ivory tower approach, but by analyzing the applications that were in use in businesses across the world.

With the active support of government and commercial buyers alike, vendors the UNIX system community began to converge on products that implement the Single UNIX Specification, and now all major vendors have products labeled UNIX 95, which indicates that the vendor guarantees that the product conforms to the Single UNIX Specification.

Vendors will continue to add value to the UNIX systems, particularly in areas of new technology, however that value added will always be built upon a single, consensus standard. Meanwhile, the functionality of the UNIX system was established and the mid-life crises was resolved. Suppliers today provide UNIX systems that are built upon a single, consensus standard.

It is also important to remember that even when variance among UNIX systems was at its worstmaximum, IT professionals agreed that migration among UNIX system variants was far easier than migration among the proprietary alternatives.

Now with UNIX 95 branded products available forrom all major UNIX systems vendors, the buyer can for the first time buy systems from different manufacturers, safe in the knowledge that each one is guaranteed to implement the complete functionality of the Single UNIX Specification and will continue to do so.

UNIX system suppliers can assure customers that they own a standards-based system by registering them to use the Open Brandbranding their system to Open Group specifications. Below is a list of suppliers who have given users this guaranteeassurance.

UNIX 95 Registered Products

DIGITAL: Digital UNIX® Version 4.0 running Digital's AlphaStations and Digital's AlphaServers

HITACHI: Hitachi 3050RX, 3500/3X, 3500/4XX running HI-UX/WE2 Version 06-01 and later HITACHI: Hitachi 3500 running HI-UX/WE2 Version 07-01 and later

Hewlett-Packard: HP-UX Release 10.20 and later on all HP9000 Series 700 and 800

IBM: IBM POWER, POWER2, and PowerPC™ Systems with IBM AIX® Version 4.2 or later

IBM: OS/390 Version 1 Release 2 or later with OS/390 V1R2 or later Security Server and OS/390 V1R2 or later C/C++ Compiler on IBM System/390 Processors that support OS/390 Version 1 Release 2

NCR: NCR UNIX System V Release 4 MP-RAS Release 3.02 or later on NCR WorldMark Series & System 3000 Series

NEC: UX/4800 R12.3 and later on UP4800 and EWS4800 Series

SCO: SCO UnixWare® Family R2.1.1 and later for single and multiprocessor Intel™ 386/486 or Pentium® PCs conforming to PC/AT architectures

SNI: Business Servers running BS2000/OSD V3.0 and higher

SNI: Reliant UNIX V5.43 running on RM Server Family, all Models RM200/300/400/600

Siemens Pyramid: Reliant UNIX Version 5.43 running on Reliant RM1000® Cluster Server

SUN: Solaris 2.6 on SPARC based systems

SUN: Solaris 2.6 on x86pc based systems


What do buyers expect from an Open Systems strategy based on the UNIX system? In 1996 EvansGroup Technology carried out research among computer system buyers in the United States, UK and Europe.

When asked about the benefits of open systems, they key issues of compatibility, flexibility and cost emerged.

The table below shows how respondents ranked the various benefits of Open Systems.

Benefits of Open Systems




Freedom to choose IT from different vendors


Products from different vendors work together


Access across multi-vendor environments


Protect investment in existing computer systems


Ability to use/share information anywhere in the world


Cost savings


Interoperability/portability across various platforms


Organizational change not constrained by IT system


Cost of ownership



The UNIX System and Microsoftâ Windows NTâ

It is common these days to read analysts' accounts and IS professionals' experiences that compare and contrast the UNIX system with Microsoftâ Corporation's latest operating system, called Windows NTâ. Opinions vary, of course, but a number of common themes have emerged. The key differences between these operating environments are as follows:

The UNIX system today is more robust, reliable and scalable than its younger cousin, NT. Analysts say this observation, which is widely reported from many different viewpoints, makes practical sense. Engineers at Microsoft are retracing the steps that the UNIX system has completed. How else could it be?

In sharp contrast to the open standards that define the of the UNIX system, Windows NT technology remains fiercely proprietary. Microsoft remains ambivalent to the world of standards. Choosing NT entangles customers with nonstandard utilities, directories, and software tools that do not conform to any de jure or consensus standards.

The UNIX system today is available on a wide spectrum of computer hardware. Particularly when high performance is at issue, hardware suppliers suggest the UNIX system, rather than Windows NT. TCurrently, the primary appeal of NT is for low-end, office-centered, departmental applications.

Unit shipment growth rates for Windows NT exceed the rates for the UNIX system, which is to be expected for a new product. However, revenue growth in UNIX systems sales is much higher than NT. It is reasonable to expect Windows NT to take a share in the operating systems market, along with other more specialized operating systems. There is no evidence today to indicate that NT will be dominant; in fact, most IT professionals predict that it will not.

Windows NT Server 4.0 is still not a full-function server operating system. While it does support multi-user computing via third-party add-on tools, it lacks certain fundamental features that the UNIX system is known for providing, such as directory services for managing user access and peripherals over a distributed enterprise network.

The presence of the UNIX system in the marketplace has been good for Windows NT. The UNIX system established the market for cross-platform client and server operating environments that NT seeks to address. In turn, NT will improve the market for UNIX systems in the future. That is, competition among UNIX system providers will be enhanced by competition with NT. The choice between open and proprietary products will be quite crisp.

Today’s UNIX System

The key to the continuing growth of the UNIX system is the free-market demands placed upon suppliers who produce and support software built to public standards. The "open systems" approach is in bold contrast to other operating environments that lock in their customers with high switching costs. UNIX system suppliers, on the other hand, must constantly provide the highest quality systems in order to retain their customers. Those who become dissatisfied with one UNIX system implementation retain the ability to easily move to another UNIX system implementation.

The continuing success of the UNIX system should come as no surprise. No other operating environment enjoys the support of every major system supplier. Mention the name UNIX system and IT professionals immediately think not only of the operating system itself, but also of the large family of hardware and application software that the UNIX system supports. In the IT marketplace, the UNIX system has been the catalyst for sweeping changes that have empowered consumers to seek the best-of-breed without the arbitrary constraints imposed by proprietary environments.

The market's pull for the UNIX system was amplified by other events as well. The availability of relational database management systems, the shift to the client/server architecture, and the introduction of low-cost UNIX system servers together set the stage for business applications to flourish. For client/server systems, the networking strengths of the UNIX systems shined. Standardized relational database engines delivered on low-cost high-performance UNIX system servers offered substantial cost savings over proprietary alternatives.

The UNIX System Tradition

For the last two and a half several decades, the UNIX systems hasve upheld a tradition of providing its customers with early access to new technologies. For example:

UNIX systems provided early access to RISC technology. Applications in CAD/CAM, multimedia, and large-scale publishing that demanded high performance workstations have always used the UNIX system platforms.

The UNIX systems provided early access to symmetric multiprocessing [SMP] computers. UNIX system-based SMP parallel processors radically improved the price/performance of midsize and high-range servers.

The UNIX systems first enabled allowed distributed transaction processing in conjunction with TP monitors from independent software suppliers. The server side of client/server technology was launched on the UNIX systemservers.

UNIX systems support the latest developments in object technology. The Common Object Request Broker Architecture [CORBA] from the Object Management Group is widely available in UNIX system environments.

The UNIX systems launched the Internet and the World Wide Web.

UNIX systems suppliers also have a proud tradition of integration with legacy systems as well as innovation to uphold. No other system can ensure that disparate systems — usually proprietary systems — can be integrated, allowing the buyer’s investment in data and information to be realized with minimal disruption and reinvestment.

Look in the short term for products that carry the UNIX 98 label to add standardized support for:

Threads, enabling applications to be written to the POSIX model.

Real-time support will be available as an option for those applications that need it.

The ability to support large bit sizes and architectures — 64 bit and larger data sizes and architectures as diverse as mainframe, RISC and PC systems.

Standard mechanisms for eliminating Year 2000 issues.

Developments underway will continue to build upon strengths in

Execution of Java applications and applets (Java VM)

Build environment for Java applications

Support for Internet Inter-ORB Protocol IIOP

Network Computer (NC) support and management

Enhancements to Directory services (LDAP), Domain Naming, File transfer, client device support (DHCP & bootp) and file services

Standardized clients, such as web browsers.

There is every reason to believe that the UNIX systems will continue to be the platform of choice for innovative development. In the near term, for example, UNIX system vendors will define the scope of Java and provide the distributed computing environment into which the Network Computer terminal [NC] will fit and enable it to thrive and grow.

How will Java and the Network Computer terminal NC will manifest themselves? The exact answer is unknown; however, in open computing, the process for finding that answer is well understood. The UNIX system community has set aside (via consensus standards) the wasteful task of developing arbitrary differences among computing environments. Rather than building proprietary traps, this community is actively seeking ways to add value to the UNIX system with improved scalability, reliability, price/performance, and customer service.

Java and the Network Computer terminal NC offer several potential advantages for consumers. One key advantage is a smaller, lighter, standards-based client. A second advantage is a specification that is not controlled by one company, but is developed to the benefit of all by an open, consensus process. Thirdly, greater code reuse and a component software market based on Object technology, such as CORBA and Java. All of these options and more are being deployed first by members of the UNIX system community.

Industrial Strength UNIX System

Today's UNIX system is robust, scalable, and it continues to provide uniform access to a wide variety of computing hardware. For these reasons the UNIX system continues to be the operating system of choice for mission-critical systems. The UNIX system is the key enabler for enterprises that wish to keep switching costs as low as possible. That is, the UNIX system remains the only open alternative to locking in on a proprietary operating system.

Scalability is here today, enabling application to run on small-scale systems through to the largestr servers necessary. The UNIX system is available on hardware ranging from low-cost PC-class servers on through parallel architectures that harness together 60 or more processors. This range is wider and the choices of hardware more cost effective than any other system. The UNIX system is the only option for Massively Parallel Processing (MPP).

A robust operating system is tough enough to perform successfully under a variety of different operating conditions. By virtue of its worldwide deployment by an international community of system vendors, the UNIX systems hasve earned the reputation for robustness. UNIX systems thrive in multilingual environments supporting business, engineering and network management applications.

Uniform operating system services are at the heart of the standardized UNIX system. Many enterprise systems are assembled with hardware from several different sources. Atop these different hardware platforms, the UNIX operating system provides a uniform platform for database management systems and application software.

The market for the UNIX systems continues to expand. IDC estimates the market at US$ 39 billion in 1996 and forecasts the market to be US$ 50 billion in the year 2000. In addition, the installed base of the UNIX systems has an estimated value of US$ 122 Bbillion. These market estimates lead to several conclusions about the UNIX systems, as follows:

An annual market of US$ 39 billion is large enough to remain attractive to many suppliers and to provide sufficient revenue to fund continuing high levels of investment in support and product enhancement.

The UNIX system’s growth rates, which appear modest in comparison to the unit shipment growth of newer products, are anchored by an enormous installed base. High unit shipment growth rates are typical of new entries in a marketplace.

In key benchmarks and mission-critical applications, the UNIX systems consistently performs better.

The UNIX system is the dominant software platform for Relational Database Management Systems.

Investment in developing and enhancing UNIX system products is significantly larger than in any other operating environment.

Single UNIX Specification

Today, the Open Group’s UNIX 95 brand system brand may be applied to any operating system product that is guaranteed to as meeting the Single UNIX Specification. The Single UNIX Specification single-user specification is designed to give software developers a single set of APIs to be supported by every major version of UNIX system.

The most significant consequence of the Single UNIX Specification initiative is that it shifts the focus of attention away from many incompatible UNIX system product implementations on to compliance with a single, agreed-upon set of APIs. If an operating system meets the specification, and commonly available applications can run on it, then it can reliable viewed as open.

This means that the qualities that made UNIX systems the candidate for the open systems engine room in the first place have now been applied to the Single UNIX Specification. Now, a new generation of open, X/Open UNIX system branded products is on the way. These products will be based on proven UNIX systems technology. Full compliance with the Single UNIX Specification complements that proven technology with vendor implementations that can compete on product features such as reliability, scalability, multiprocessing, applications availability and support.

So, the future looks as though it will be about a set of sturdy and dependable specifications standing as a firm foundation upon which many competing product implementations will be built.

By developing agreeing a single specification for the UNIX systems, The Open Group and the computer industry have completed the foundations of open systems.

Now The Open Group is proceeding with its mission of building the basis for open, interoperable computer systems.

The next version of the Single UNIX Specification, known as Version 2 was announced in March 1997. Products guaranteed to conform to this specification will carry the label UNIX 98.

Single UNIX Specification, Version 2 enhancements

Version 2 of the Single UNIX Specification, Version 2 contains the following enhancements:

Year 2000 Alignment - changes to minimize the impact of the Millennium Rollover.

Threads: POSIX 1003.1c-1995. The Threads extensions permit development of applications to make significant performance gains on multiprocessor hardware.

Large File Summit extensions to permit UNIX systems to support files of arbitrary sizes, this is of particular relevance to database applications.

Networking Services: The specifications will be aligned with the POSIX 1003.1g standard.

MSE: The Multibyte Support Extension is now aligned with ISO C amendment 1, 1994.

Dynamic linking extensions to permit applications to share common code across many applications, and ease maintenance of bug fixes and performance enhancements for applications.

N-bit cleanup (64 bit and beyond), to remove any architectural dependencies in the Single UNIX SpecificationUNIX system specification. This is of particular relevance with the ongoing move to 64 bit (and beyond) CPUs.

The real-time extensions are an optional feature group, allowing procurement of X/Open real-time systems with predictable, bounded behavior.

Inclusion of the existing specifications for the graphical user interface, CDE as an option in the UNIX 98 brand.

Benefits for Application Developers

A single standard for the Greater consistency amongst UNIX operating systems means:

Improved portability.

Faster development through the increased number of standard interfaces.

More innovation is possible, due to the reduced time spent porting applications.

Benefits for Users

The Single UNIX Specification will evolve and develop in response to market needs This is an evolution of the XPG4 UNIX system (UNIX 95) brand, therefore protecting users investment in existing systems and applications. The availability of the UNIX systems from multiple suppliers gives users freedom of choice rather than being locked in to a single supplier. And the wide range of applications - built on the UNIX system’s strengths of scalability, availability and reliability - ensure that mission critical business needs can be met.

In Summary, …

When the history of the information age is written, the extraordinary dynamics of the UNIX system marketplace will be seen as playing an important role. The UNIX system was developed at just the right time and place to be the critical enabler for a multitude of revolutions in information technology. Client/server architectures, the Internet, object databases, heterogeneous transaction processing, and Web computing all emerged on the shoulders of the UNIX system.

Most importantly, the UNIX system continues to be a driving force for innovation because of its commitment to standards. When proprietary differences are set aside, and with the wide implementation of the Single UNIX Specification they are set aside, suppliers compete by adding value. This fundamental tenet is the reason that the UNIX systems hasve thrived – and will continue to thrive in the years to come.

# # #

UNIXâ is a registered trademark of The Open Group.

Microsoftâ and Windows NTâ are registered trademarks of Microsoft Corporation.


This white paper was developed by the UNIX Systems Cooperative Promotion Group, which is comprised of member companies that include Digital Equipment Corporation, SCO, Siemens Pyramid Information Systems, Sun Microsystems and The Open Group. The UNIX Systems Cooperative Promotion Group is a non-profit organization of vendors committed to the development and promotion of the UNIX operating system.


Contact: Kimberly Pepper, EvansGroup Public Relations, 190 Queen Anne N.,

Seattle, WA. 98109; (206) 270-4642; (206) 270-4656 Fax;


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