Windows Support for Portable Computers
Microsoft Windows 2000 and Windows XP provide robust power management and fully dynamic Plug and Play support. Based on the OnNow power management architecture and the ACPI specification, support in Windows is optimized for ACPI systems.
On This Page
 | Windows Plug and Play Support for Portable PCs |
| Windows Basic Legacy Support for Portable PCs |
| OEM-Specific Legacy Solutions and Windows |
Windows Plug and Play Support for Portable PCs
The combination of ACPI, OnNow, and Microsoft Windows Plug and Play delivers the following support for portable computers:
| • | Hibernation | ||||
| • | Low-power system states (sleep states) | ||||
| • | Low-power processor states | ||||
| • | Low-power device states | ||||
| • | Battery management; including support for:
| ||||
| • | Hot and warm docking and undocking | ||||
| • | Hot-swapping of IDE and floppy devices | ||||
| • | Hot-swapping of PC cards and CardBus cards |
Based on these features, the Microsoft Windows Logo Program requires that all new designs implement ACPI and OnNow as of April 1, 1998. In fact, many portable computers have been designed with ACPI and OnNow since September 1997.
Windows Basic Legacy Support for Portable PCs
For the installed base of non-ACPI portable computers, Windows also includes Basic Legacy Support, which does not offer the full features described above, but enables the use of Windows on many portable computers. This capability is intended to replace the OEM-specific power management and Plug and Play implementations that have become available for Windows NT 4.0. These implementations--which consist of various combinations of BIOS code and custom device drivers--cannot be fully supported in Windows and will therefore be removed by Windows Setup during upgrades.
Basic Legacy Support provides the following features:
| • | Hibernation |
| • | Suspend/Resume by way of the APM BIOS |
| • | Basic Battery Level reporting by way of the APM BIOS |
| • | Enumeration of system-board devices by way of the Plug and Play BIOS at boot time only (static numeration) |
| • | Cold docking/undocking by way of Hardware Profiles |
Microsoft ships Windows with the Basic Legacy Support disabled, and end users can enable it if they want to. OEMs must test their systems to determine which have compatible APM and Plug and Play BIOS implementations.
OEM-Specific Legacy Solutions and Windows
Notice that Basic Legacy Support explicitly does not provide support for the following:
| • | Low-power processor states (the APM CPU Idle function) |
| • | Low-power device states (the APM Set Device Power State functions) |
| • | Hot or warm docking (Plug and Play BIOS Dock_Changed functions) |
| • | Hot-swappable IDE or Floppy devices |
| • | CardBus cards |
Important: If any of these features are supported by an OEM solution that is removed by Windows Setup, the OEM must provide customers with a replacement solution that restores the feature, upgraded to be compatible with Windows 2000 and Windows XP.