Windows NT

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Last Updated On: 08/05/2004


Introduction to Windows NT

Microsoft designed Windows NT as a business-oriented operating system with an emphasis on networkability. Two flavors of Windows NT exist, Server and Workstation. Both Server and Workstation are 32-bit operating systems with support for multitasking, multiprocessing, and multithreading. Windows NT has multi-platform support for both the Intel and the DEC Alpha architectures, and supports 32-bit Windows applications, 16-bit Windows applications, and DOS applications. There is limited support for OS/2 and POSIX applications. Many Windows 95/98 applications run under Windows NT provided that they do not make direct requests to the hardware (this is very common with games that write directly to the video memory for faster performance). Neither version of Windows NT has plug-and-play support. We are primarily concerned with Windows NT Workstation.

Server is the more fully-featured version of Windows NT, and is more expensive. Workstation, on the other hand, is typically used on client machines that request services from a Windows NT Server. Internally, the two versions are almost identical. Their underlying architecture is the same, and they are difficult to distinguish from the desktop. However, Windows NT Server provides additional network support software and licensing capabilities. The main differences are listed below:

Windows NT Sever:

  • Support an unlimited number of incoming and outgoing connections.
  • Supports up to four processors (without special software).
  • Fault tolerance in the form of disk mirroring, duplexing, and striping with parity.
  • Supports up to 256 incoming RAS connections.
  • Includes Dynamic Host Configuration Protocol (DHCP), Domain Name Service (DNS), and Windows Internet Naming Service (WINS) services.
  • Can run as a primary domain controller (PDC).
  • Includes Internet Information Server (IIS).
  • Minimum hardware requirements of 16 MB RAM and 124 MB hard disk.

Windows NT Workstation:

  • Support an unlimited number of outgoing connections, however only ten incoming connections.
  • Supports up to two processors.
  • No fault tolerance capabilities.
  • Supports only one incoming RAS connection.
  • Can act only as a DHCP, DNS, or WINS client.
  • Includes Peer Web Services.
  • Minimum hardware requirements of 12 MB RAM and 117 MB hard disk.

The following is a chart displaying the areas in which Windows 95 and Windows NT differ.

Windows 95
Windows NT Workstation
Security Windows 95 has password security on shares. Other security is minimal Windows NT offers security through NTFS to a file level, along with a mandatory logon process.
Application Support Windows 95 contains 16-bit code to provide support for older DOS applications and games. 16-bit applications are more likely to crash the OS. Windows NT contains no 16-bit code. Does support older applications as long as they do not try to directly access hardware. Improved stability.
Plug-n-Play Windows 95 has support for plug-n-play devices. Windows NT 4.0 has no plug-n-play support.
Tools Windows 95 has few built-in system tools and configuration utilities. Windows NT has many tools that can be utilized for troubleshooting and configuration.
Overhead Windows 95 requires less system power and disk space. Windows NT has more stringent hardware requirements.

Windows NT 4.0 Architecture

The below diagram shows the different components of the Windows NT 4.0 Workstation architecture. Please note that all processes exist either in the Kernel or User Mode. The Kernel Mode is the heart of Windows NT. Only privileged processes are allowed to run there. The User mode, as its name implies, is where the higher level user applications and processes are executed.