Preparing for ACPI and OnNow Design

Windows NT Server 5.0 will include support for ACPI, which supports operating system–based power management and Plug and Play system–configuration capabilities. This guide introduces some of the system and device capabilities required for hardware that is Plug and Play-compliant when used with Windows NT 5.0.

The goal of the OnNow design initiative is to ensure that all system components work together to enable robust and reliable system configuration and power management. The operating system and applications work together intelligently to deliver effective power management. All devices connected to the system or added by the user participate in the device power management scheme.

The OnNow design initiative means new requirements for the operating system, applications, device drivers, and hardware in order to deliver transparent power management and improved integration of components. The changes include:

• Enhanced core operating system functionality for power management.
  
  
• Windows Driver Model (WDM), which supports power management and Plug and Play, and provides a common set of I/O services and binary-compatible device drivers among Windows® 98 and Windows NT for targeted device classes (audio, input, video, and still imaging) and bus classes (USB and IEEE 1394).
  
  
• A new system interface for operating system–directed power management and Plug and Play. The ACPI design also provides future extensibility and improved system integration.
  
  
• Device and bus hardware power management interfaces and state definitions.
  
  
• An application architecture that allows applications to integrate into power management of the system.

The ACPI specification defines a flexible and abstract hardware interface that enables a wide variety of server systems to implement power and thermal management functions while meeting the cost and feature requirements of the target market. ACPI also provides device configuration and generic system-event mechanisms for Plug and Play, unifying the power management interface with the Plug and Play interface.

The ACPI implementation is independent of the processor architecture and enables the operating system to direct power management throughout the system.

For more information about ACPI and the OnNow design initiative, see the OnNow web site at http://www.microsoft.com/hwdev/onnow.htm.