OnNow and ACPI for PC 98

The OnNow design initiative is a comprehensive, system-wide approach to system and device power control based on a group of new specifications. OnNow is the term for a PC that is always on and responds immediately to user requests or other events, but it appears to be off when not in use.

Since PC 97 Hardware Design Guide was published, the following industry advances have been made on the OnNow design initiative:

• Completion of Advanced Configuration and Power Management Interface Specification, Revision 1.0. The ACPI specification defines a new cross-platform interface to the system board. This interface enables the operating system to implement operating system–directed power management and Plug and Play on a broad array of PCs, including servers, business systems, and consumer PCs. ACPI allows system manufacturers to build systems consistent with the OnNow design initiative for instantly available PCs.

Intel and other system-board manufacturers are now implementing the ACPI specification, and OEMs are beginning large-scale manufacturing of ACPI systems.

• Completion of bus power management specifications and device class power management reference specifications for most device classes.

Specifications have been made widely available in the industry, and manufacturers are beginning to implement OnNow-based power management capabilities in their product lines.

• Implementation of ACPI support in operating systems, enabling a generic system-event mechanism for Plug and Play, configuration control, and power management.

Microsoft provides full driver-level support for the ACPI specification in Windows 98 and Windows NT 5.0 operating systems. Using the assembler, debugger, and compatibility testing tools provided by Microsoft, system manufacturers have been able to design, develop, and test ACPI chip sets, firmware, and system boards.

• Implementation of OnNow power management policy plus device driver and application interfaces so that device designers and driver writers can create and test OnNow-capable devices and peripherals.

The key design progress for OnNow and ACPI focuses on the following capabilities:

• Migration of system configuration from the Plug and Play BIOS to ACPI. ACPI leverages the Plug and Play BIOS data structures in a way that is compatible with both Windows 98 and Windows NT 5.0 but independent of processor architecture implementations.
  
  
• Migration of legacy power management from BIOS Advanced Power Management (APM) 1.2 to ACPI for Windows 98 and Windows NT 5.0.
  
  
• Clarification of design issues and requirements for hardware and software in support of the OnNow-capable PC.

Current information about specifications and progress for this initiative, including details for technical implementations, can be found on the web site at http://www.microsoft.com/hwdev/onnow.htm.