Why Have Two Desktop Operating Systems?

Microsoft Corporation

Created: July 1994

Introduction

It is important to understand that there are two distinct design points for Microsoft's family of operating systems—one centered on the mainstream system (in 1994), and another centered on the leading-edge system. It is not currently possible to have one operating system implementation that fully exploits the broad range of hardware available at any point in time. For mainstream systems (currently represented by products such as sub-notebook and entry-level desktop machines), the Microsoft® Windows® 95 design goal is to deliver responsive performance for a broad range of applications while conserving the amount of system resources used. On the leading-edge system (for example, a dual-processor workstation or multi-processor RISC server), Windows NT™ was designed to fully exploit the capabilities of the hardware and provide the most advanced services for the most demanding applications.

As a result of the requirements placed on the new enterprise solutions, all major operating system developers have recognized the necessity of moving to a micro-kernel architecture for their leading-edge operating systems. This includes Microsoft, IBM, Sun (and most UNIX® vendors), and Novell. Only Microsoft made this commitment over 5 years ago and began shipping Windows NT to developers in July 1992 with general availability in July 1993. This architecture allows vendors to enhance systems to respond to the rapidly changing requirements of the business solutions being developed, while maintaining flexibility to exploit new hardware and peripherals.

Both Windows 95 and Windows NT Workstation provide a common base of functionality that is required by all customers, including ease of use, power, connectivity, and manageability. Microsoft is committed to, and will deliver, parity in basic functionality (such as the user interface) to each platform as quickly as possible. The further differences between the two platforms are a result of their different design goals. Windows 95 is focused on making computing easier for anyone using a wide range of personal and business applications on desktop and portable computers. To protect their current investment, these users require the highest level of compatibility with today's applications and device drivers.

Windows NT Workstation is focused on providing the most powerful desktop operating system for solving complex business needs. For developers; technical, engineering, and financial users; and business operations application users, it delivers the highest level of performance to support the most demanding business applications. It also provides the highest levels of reliability, protection, and security for those applications that you can't afford to have fail while exploiting the latest hardware innovations such as RISC processors and multi-processor configurations. This focus on solving business needs is also reflected in the emphasis on maintenance and regular system updates.

Over time, as mainstream machines become more powerful, technologies implemented first on the leading-edge Windows operating system product will migrate to the mainstream product. Sometimes technical innovations will appear first on the mainstream product, due to timing of releases or because some features are focused on ease of use for general end-users. The guiding principle for product planning is for the leading-edge product to provide a superset of the functionality in the mainstream product.

For application developers, Microsoft has only one Windows programming platform, defined by Win32® (the 32-bit Windows application programming interface) and OLE. By following a few simple guidelines, developers can write a single application that runs across the Windows operating system product family. If they wish, developers can target specific operating system products because the functionality they provide is important to their particular application, but that is not a requirement.

Usage Scenarios

The decision about which platform to deploy should be based on what tasks people are trying to accomplish. The two platforms provide a very complementary set of capabilities that can accommodate a broad range of use scenarios. Consider the following examples:

Similarities

Benefit/Feature Windows 95 Windows NT Workstation
Ease of use
Auto-detection of hardware during installation and configuration Yes Yes
Next-generation Windows user interface (redesigned usability) Yes Next release
Plug and Play technology that lets you add hardware without reconfiguring your computer Yes Next release
Power
32-bit, pre-emptive multitasking design provides responsiveness between applications that you need to work more efficiently. No more waiting. Yes Yes
Win32 API for application development, OLE 2.0 for linking data across applications Yes Yes
Connectivity
LAN connectivity and peer-to-peer networking, with all popular protocols including TCP/IP, IPX/SPX, and NetBeui Yes Yes
Open networking architecture provides choice of clients, transports and drivers and extensibility for support of third-party networking applications Yes Yes
Remote built-in access services to give you remote access to your workstation Yes Yes
Manageability
Open system management architecture provides infrastructure for third-party system management solutions Yes Yes
Supports existing and emerging system management standards (SNMP, DMI) Yes Yes
Desktop user profiles (can be modified by anyone on the system) and monitoring tools Yes Yes
Application support
Runs Win16 applications Yes Yes
Runs Win32 and OLE 2.0 applications Yes Yes
System and peripheral support
Fully exploits 386DX, 486, and Pentium platforms Yes Yes

Differences

Benefit/Feature Windows 95 Windows NT Workstation
Protection and security
Complete crash-protection between Win16 applications by running Win16 applications in separate address spaces No Yes
Offers C-2 certifiable user-level security over access to a standalone workstation. Files, folders, and applications on both desktop and server can be made "invisible" to specific users. No Yes
Secure user profiles to control access to desktop, applications, and system configuration files No Yes
Data protection through transacted file system No Yes
Has automatic recovery from a system failure No Yes
Application support
Runs MS-DOS® applications Complete support Most
Supports multiple file systems beyond the MS-DOS FAT file system—HPFS, NTFS No Yes
Uses OpenGL graphics library to enable advanced 3-D graphics next release Yes
Runs IBM® Presentation Manager® (through 1.3) and POSIX 1003.2 applications No Yes
System and peripheral support
Runs MS-DOS device drivers Yes No
Runs Win16 device drivers Yes No
Supports disk compression Yes Yes
Runs on PowerPC™, MIPS, and DEC Alpha based RISC systems No Yes
Supports multi-processor configurations for scaleable performance without changing operating system or applications No Yes
Support and service
Quick-fix engineering teams to solve problems in critical sites (issues that block business systems usage or deployment) No Yes
Monthly maintenance releases posted to electronic services (e.g., CompuServe®, Internet) No Yes
Quarterly service pack releases: Distribution vehicle (CD-ROM and floppy) for maintenance releases No Yes