Windows NT Protocols, Subsystems Go by the Boards in x64

Some of Windows NT's oldest subsystem and protocol friends will be left behind when the codebase moves to x64.

Microsoft uses the x64 name to designate operating systems supporting the 64-bit extensions to the x86 architecture. The operating systems support the AMD64 architecture and Intel processors featuring Extended Memory 64 Technology (EM64T). Microsoft's x64 versions of Windows Server 2003 and Windows XP are currently in the Release Candidate testing stage and are expected to ship in the first half of this year.

In a recent post on the Windows Server Division's new blog, product manager Ward Ralston discusses some legacy subsystems and protocols that are dropped. On top of the list is the 16-bit subsystem.

"Keep in mind that some 32-bit programs still use 16-bit installers…..Fortunately, 64-bit Windows detects most of these installers and transparently loads a 32-bit version that ships with the operating system," Ralston, a product manager for Microsoft's Windows Server 2003 64-bit editions, writes.

Also out are the MS-DOS subsystem, OS/2 subsystems, POSIX subsystem (Portable Operating System Interface for Unix), IPX/SPX, Apple Talk, Services for Macintosh, DLC LAN, NetBEUI, IrDA and OSPF.

In a separate post, Ralston noted that Microsoft is proceeding with plans for deeper support of Intel Itanium, a different 64-bit architecture that Microsoft has supported for several years. Windows Server 2003 Service Pack 1 still includes the IA-32 Execution Layer Driver for Itanium, a software driver that improves performance of 32-bit applications running on Itanium-based systems. The driver translates Intel architecture 32-bit code into native Itanium architecture code before executing it.

The driver has also been available as a separate download at

SP1 for Windows Server 2003, the code foundation for the x64 editions, is in Release Candidate 2 testing.

About the Author

Scott Bekker is editor in chief of Redmond Channel Partner magazine.


  • Office Mobile Apps To End as Microsoft Highlights New Office App

    Microsoft plans to end support for Windows 10 Mobile applications on Jan. 12, 2021, according to a Friday announcement.

  • Is Microsoft Finally Reinventing Office?

    Microsoft is testing out a new technology called "Fluid Framework." It could mean that Brien's dream of one Office app to rule them all might soon become reality.

  • Azure Active Directory Connect Preview Adds Support for Disconnected AD Forests

    Microsoft on Thursday announced a preview of a new "Cloud Provisioning" feature for the Azure Active Directory Connect service that promises to bring together scattered Active Directory "forests."

  • Microsoft Defender ATP Gets macOS Investigation Support

    The endpoint and detection response (EDR) feature in Microsoft Defender Advanced Threat Protection (ATP) has reached the "general availability" stage for macOS devices.

comments powered by Disqus

Office 365 Watch

Sign up for our newsletter.

Terms and Privacy Policy consent

I agree to this site's Privacy Policy.