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System ToolsAdvanced Configuration and Power Interface (ACPI)
Window 98 provides an updated Power Management functionality for both fully On-Now systems and for legacy Power Management as provided by Advance Power Management (APM) version 1.1 and 1.2. Using the Win32 Driver Model, power management for devices has been incorporated into every WDM driver. This allows Windows 98 to communicate with each device to determine its power state and if it is safe, put it into a low-power mode.
ACPI was designed to address the shortcomings of previous power management plans. ACPI requires changes in both the BIOS and the chipset on the motherboard for full implementation. It should be noted, during the beta testing, only one such motherboard chipset, the Intel 430TX, was available to the public. There was not a publicly available BIOS that supported ACPI. There maybe instances where the customer will need to upgrade their BIOS for full ACPI functionality.
ACPI names four power management states, D0-D3. The states are related to each other in terms of power used versus context retained. Context is defined as information on the condition of the device. For example, a device that loses its entire context will need to be reinitialized to resume functionality. Each state is defined in the ACPI specification as shown below.
Simply put, D3 is considered off while D0 is considered fully on. The D1 and D2 states are not clearly defined except in relation to the other states.
Usage and Configuration
The configuration of the system wide power management is controlled through the Control Panel – Power Management. Windows 98 comes with three preset Power Management configurations: Home/Office Desk, Laptop and Personal Server. Customers can create more schemes by using the Save As button. Customers can also set suspend time for Energy Star compliant monitors and the IDE hard drive spin down time. If Windows 98 is reinstalled, the settings are reset to the default.
Power Management – Advanced Tab
The Advanced tab will allow the customer to control the System Tray icon, passwords (which is the same as the screen saver password) and to enable the Wake on Ring setting. The Power Buttons settings will allow the choices of Shutdown and Standby modes.
Power Management for Laptops
The dialogs for Power Management for laptop are similar to those for desktop except for the addition of the Alarms and Battery Meter Tabs. The main difference is the customer will be able allowed to change settings based on the computer is running on batteries.
The Alarm Tab will allow the customer to set when an alarm should be triggered and what action to take. The choices of actions are Suspend and Shutdown.
The Battery Meter shows the current sources of power and the percentage remaining. Turning Show Details off will show the total percentage of battery power remaining.
APM in the Device Manager
These settings effect how Windows 98 access with Power Management can be made in the Device Manager. By choosing System Devices – Advanced Power Management Support – Properties – Settings, the customer is able to configure Windows 98 to use APM 1.0 mode (for older power management implementations) and to disable power status polling. Both of these changes should only be made if issues arise using the default settings.
Points to Remember