Many people believe that all advanced 32-bit desktop operating systems are roughly equivalent in capabilities, and yet the underlying architecture and design choices influence the appropriateness of any operating system that is to be selected for an application.
For example, Microsoft's Windows NT™ Workstation and IBM's OS/2® Warp are both advanced 32-bit operating systems which are often compared in terms of the features and benefits they offer to users.
Evaluators of operating systems should consider at least three key requirements when selecting an advanced operating system.
This bulletin addresses these three key evaluation points using OS/2 Warp or UNIX to illustrate some of the key differences.
Operating systems should be designed to be bulletproof. This section focuses on the basic architecture of Windows NT Workstation and Warp. The architecture directly impacts many characteristics such as reliability, scalability, and performance.
One of the primary design goals for Windows NT Workstation 3.51 was to provide the most robust operating system available for the desktop computer. Reliability results in reduced system downtime which allows users to be more productive and reduces overall MIS support costs.
The Windows NT architectural model was designed such that applications are protected from each other and from the base operating system, making the operating system extremely robust.
By definition, 32-bit applications run in their own memory spaces. Windows NT Workstation 3.51 also supports the ability for 16-bit applications to each have their own memory space using the multiple virtual DOS machine (MVDM) capability. This ensures that all applications are completely protected from one another.
Windows NT further ensures that the base operating system is protected from errant applications. Using a client-server architectural model, applications communicate with environment subsystems and the NT Executive by utilizing a message-passing facility in the kernel.
Figure 1. Windows NT Client-Server Model
Processes run in either non-privileged (user) or in privileged (kernel) modes. All environment subsystems and applications run in user mode, each running in its own protected memory address space. All critical operating system processes such as memory management and thread scheduling run in kernel mode.
All critical operating system and window manager data structures are protected from corruption by any application. Only the operating system and window manager code may directly modify this critical data.
This design improves overall system reliability since applications, environment subsystems, and the kernel are completely protected from one another.
Similar to Windows NT Workstation, Warp is a 32-bit, preemptive multitasking operating system. It also supports separate virtual DOS machines (VDMs) for both 16- and 32-bit applications.
However, Warp is not based on a client-server architectural model. While protecting applications from one another, Warp does not protect the operating system from errant applications. The basic architecture of OS/2 Warp is outlined in the diagram below.
Figure 2. Warp architectural model
The architectural model used by Warp results in lower memory requirements than Windows NT Workstation. However, large bodies of Warp system code and data are visible to all processes in globally shared memory. Many portions of this memory are writable by all applications, including system wide data structures for the window manager, graphics engine, and non-kernel system components (the shell, desktop, object model). Thus, application errors can corrupt the vulnerable portion of the address space that is shared between all processes. When this occurs it can cause system failure, loss of data, data corruption, or system crashes.
Users of advanced operating systems usually have to find ways to integrate their systems into larger networks and to maintain compatibility with existing applications. Just as important, they need to ensure that their data remains secure from accidental loss or malicious tampering once they're on a network.
In heterogeneous environments, it is critical to connect workstations to larger networks. A significant difference between Windows NT Workstation and OS/2 Warp is integrated networking. Networking capabilities have been built directly into the Windows NT platform since its first release in 1993.
Today, Windows NT Workstation provides more network and protocol support than any other desktop operating system. The advantages of this for today's business user are multi-fold. First, Windows NT Workstation can be easily integrated into almost any existing network environment without having to purchase additional software - this saves both time and money.
Second, Windows NT Workstation provides users with the element of choice. Multi-protocol support allows users to run any number of protocols simultaneously to access networked resources. Standard with the product, Windows NT Workstation includes support for more that 15 network protocols including the following:
Networking is also important from remote sites for users that need to access network files or to remotely connect to a network. Windows NT Workstation provides a very robust set of Remote Access Services (RAS). The RAS implementation allows multiple protocols to be supported including TCP/IP (with SLIP or PPP), IPX/SPX and basic NetBEUI. Additional key RAS features include the following:
All of this network functionality is included in the base product. This ensures that every user receives the same feature set - including the same advanced networking support.
IBM offers several different versions of Warp, including the new OS/2 Warp Connect. This is a separate product. Early information on this product indicates that it will include a sub-set of the networking support offered by Windows NT Workstation.
UNIX also offers built-in networking support, typically based on TCP/IP protocols. To connect to mainstream PC-based networks, UNIX vendors require additional products, making it more difficult to achieve universal connectivity.
Windows NT Workstation 3.51 has been designed to provide complete protection for both line-of-business applications and critical business data. Because of its advanced security model, system administrators can ensure that users do not damage key line of business applications or change system files unless they are given permission to do so. The business advantage is clear: corporations that deploy Windows NT Workstation on the desktop will spend less resources on help-desk and support.
A priority for many users is protecting private, sensitive data from being lost or exposed. With Windows NT Workstation, large corporations, banks, hospitals, and government agencies can be assured that critical business data is protected from malicious tampering, unauthorized access, and user error.
One of the elements at the core of the Windows NT architecture is integrated security. In its simplest form, Windows NT Workstation includes a secure logon sequence (using the Ctrl-Alt-Del key sequence). This sequence prevents rogue applications from trapping the username and password sequence. Coupled with the account lockout capability, failure to enter the correct password after a specified number of attempts results in that user being prevented from gaining access.
Windows NT Workstation ensures data protection with the ability to define the discretionary level of access control that users can have to the system. The Windows NT security model allows users to apply security to both networking and all system objects. The native Windows NT file system (NTFS) provides this security down to the file level.
Data protection is straightforward with Windows NT. Before an application or process can open a handle to any object - including file or data objects - the Windows NT security system transparently verifies that the process has the appropriate authorization level. Windows NT ensures that no process can access a file unless the file's owner or a system administrator permits it.
Windows NT Workstation also supports multi-user capabilities while retaining a high level of security. Several users can share a single computer system while having total access-control over their personal files. Further, multi-user capabilities allow multiple users to have unique desktops, program groups, and other capabilities.
OS/2 Warp does not include built-in security. Furthermore, Warp does not support the same kind of multi-user capabilities. It can neither prevent unauthorized users from gaining access to critical business data nor control the type of access granted to authorized users.
Investments in existing applications are also protected with Windows NT Workstation. Windows NT provides a standard, comprehensive set of protected environment subsystems that support most applications available today.
With Windows NT Workstation, users can run any of these applications. Users with 16-bit applications get the full benefits of true preemptive multitasking using multiple virtual DOS machines (MVDM). And, users will still get complete support for OLE in this environment even between 16-bit applications in separate address spaces.
Moreover, the Windows NT is open to 3rd party vendors who desire to provide even stronger compatibility between different environments. For example, at least one ISV has already written environment subsystems that enable UNIX SVR4.2 applications to run within the Windows NT platform.
In contrast, OS/2 Warp does not support the full Win32 API programming environment. Already, there are over 1,200 Win32 applications available and, with the near-term availability of Windows 95, there will be thousands more within the next 12 months.
UNIX operating systems also fail to support the Win32 API. There have been various efforts to include Windows application support in UNIX, such as WABI, but these do not offer full compatibility.
Selection of a strategic operating system is not a decision that is to be taken lightly. In addition to consideration of immediate requirements, long-term selection criteria such as broad developer and hardware support, directions for added value, and other characteristics must also be evaluated.
Application support is a key part of any operating system evaluation. The Win32 API is Microsoft's long-term development interface for applications vendors. Beyond offering compatibility through the environment subsystems previously discussed, users can take advantage of the new generation of powerful 32-bit applications which run on both Windows NT Workstation and Windows 95.
Momentum for native Windows NT applications is growing quickly. Support from industry leaders include the following applications that are shipping today or are soon to be available:
Personal Productivity Applications
Engineering and Scientific Applications
Developer Tools
The complete list of available Win32 applications is available on various on-line services in addition to Microsoft's own FTP Server on the Internet at ftp.microsoft.com.
The Win32 API is not native to the Warp operating system. Warp will not run the new generation of applications being designed for both Windows NT Workstation and Windows 95. This will present an issue for users that want to take advantage of this new API.
Windows NT Workstation has been tested and certified with over 4,700 PCs worldwide that include the mainstream Intel-based desktop systems offered today by computer hardware manufacturers. Just as important, Windows NT Workstation offers a scaleable path to high-end, workstation-class machines. This path includes support for Symmetric Multiprocessing (SMP) and RISC-based systems. Today, Windows NT supports systems based on the common MIPS and Alpha AXP microprocessors. Windows NT Workstation will also be available for the PowerPC in the Spring of 1995.
This type of broad system support ensures that users can choose the right computer hardware for their business solutions based on their needs. Central to this capability is the fact that the same base feature set is available across all platforms so that users don't need to worry about subtle differences. Windows NT Workstation is certified on more systems than Warp or any vendor's version of UNIX.
IBM currently only sells Warp for single processor, Intel-only computer systems. IBM has recently announced support for the PowerPC, but it will not be available until late in 1995. Today, if users need SMP support, they need to use an older version of the operating system, OS/2 2.11 for Symmetric Multiprocessing. This version has been sharply criticized for its poor I/O performance.
Advanced features within operating systems point to a vendor's willingness to invest in key new technologies. Applications vendors look to these advanced features to keep their products moving forward as well.
Advanced features, such as an asynchronous input queue, and preemptive multitasking for 16- and 32-bit applications allow users to get the most out of their applications. The preemptive multitasking model used by Windows NT ensures that no single process monopolizes system processor(s). Rather, Windows NT Workstation will schedule the various threads evenly. For users that run more than one application at a time, this scheduling increases overall productivity.
Windows NT has further been designed with an open memory model, eliminating memory resource limitations. In fact, Windows NT Workstation can address up to 4 GB of real memory. In other words, the operating system has been designed such that users can manage and manipulate very large amounts of data without running into resource limitations.
Windows NT Workstation already includes key technologies being implemented in hundreds of applications. In addition to the Win32 API, Windows NT Workstation offers complete support for the OLE object capabilities, OpenGL, Unicode, and other advanced functions.
With the OLE implementation in Windows NT Workstation 3.51, applications can seamlessly share resources and data dynamically across both 16- and 32-bit applications. This functionality is also supported when applications are running in their own separate memory spaces.
OpenGL is an operating system independent, industry-standard programming interface for three-dimensional color graphics. It is typically used for engineering, visualization, simulation and other graphics-intensive applications. This high-end feature is critical to many high-performance graphics applications. The availability of OpenGL on Windows NT Workstation marked the first time advanced graphics capabilities were available on PCs.
Unicode character handling enables developers to write one application which can run natively in multiple languages. Furthermore, documents can be transferred from one computer to another internationally, without garbling file and path names. The business advantage to multi-national corporations is clear: Windows NT Workstation saves time and money both in terms of custom application development and global data sharing.
Windows NT Workstation 3.511 will also support NTFS file compression as a native component to the operating system. Users can easily save disk space on their NTFS drives, with compression functionality on a per-file and per-directory basis.
In summary, Windows NT Workstation is the clear choice for business needs for both today and the future. For more information, call your nearest reseller or call Microsoft at (800) 426-9400.
© 1995 Microsoft Corporation
Microsoft, MS-DOS, Windows, Win32, and Win32s are registered trademarks and Visual C++ and Windows NT are trademarks of the Microsoft Corporation
IBM, OS/2, PowerPC are trademarks of the IBM Corporation.
Intel is a registered trademark of the Intel Corporation.
UNIX is a registered trademark of Novell Inc. in the united States and other countries, licensed exclusively through X/Open company.
MIPS is a registered trademark of MIPS Computer Systems, Inc.
Alpha AXP is a trademark of Digital Equipment Company.
OpenGL is a trademark of Silicon Graphics Inc..
Unicode is a trademark of Unicode, Inc.
Lotus is registered trademark of Lotus Development Corporation.
1-2-3 is registered trademark of Lotus Development Corporation.
2/95 Part No. 098-59609