by Dean Andrews and Larry Passo
New portable and desktop PCs feature power management capabilities that let you specify schemes for conserving power (and battery life) by shutting down devices (such as hard disks, CD-ROMs, parallel and serial ports, and so on) after a specified time of inactivity. The power management capabilities of Windows 98 allow you to control the power consumption of these various components by choosing a power scheme.
NOTE: Power schemes are collections of settings for managing the power usage of your computer.
CAUTION: Power management functionality might vary greatly from computer to computer because it depends on features that must be implemented in both the computer's hardware and its BIOS. Your computer might not support some or all of the power management features discussed in this chapter. See your computer's hardware documentation for details.
You can also adjust the power conservation settings for the various components of your computer in a power scheme. For example, depending on your hardware, you might be able to do any of the following:
Typically, you turn off your monitor or hard disk for a short period of time to conserve power. If you plan to be away from your computer for a while, you should put your computer on standby, which puts your entire system in a low-power state.
TIP: Standby is particularly useful for conserving battery power in portable computers.
CAUTION: You might want to save your work before putting your computer on standby. While the computer is on standby, information in computer memory is not saved to your hard disk. If the power is interrupted for any reason, all information in memory will be lost.
You might put your computer in hibernation when you'll be away from the computer for an extended period of time or overnight. When you restart the computer, your desktop is restored to exactly what it was when you left it.
NOTE: It takes longer to bring your computer out of hibernation than to bring it out of standby.
Several specifications for PC power management have been adopted by the computer industry over the last few years. The original specification was called Advanced Power Management (APM) 1.0, and it defined interactions among a PC's hardware, BIOS, and software that let PCs operate at different levels of power consumption, such as full power, sleep, and standby. Subsequent revisions of APM added the capability to manage the power consumption of PC Card (also known as PCMCIA) devices and portables with multiple batteries, as well as other features.
However, APM has a major limitation in that it focuses on the system board and device access information when determining whether to power down devices. The BIOS might know that a PC Card device is present, but it has no way of determining if the card is actually being used. If the hard disk is being used, the BIOS has no way of determining if it is being used by a program or if the operating system is just using it as a page file for virtual memory.
The very latest PC power management scheme, which is supported by newer computers, is called Advanced Configuration and Power Interface (ACPI) 1.0. ACPI supports the fine-tuned management of a wide variety of hardware devices.
Windows 98 supports both APM and ACPI on computers that have the appropriate BIOS and hardware for these power conservation schemes.
NOTE: ACPI is an open industry specification co-developed by Intel, Microsoft, and Toshiba.
For notebook computers, the most important aspect of power conservation is extended battery life. By setting the appropriate power management options for your notebook's hardware under Windows 98, you can operate your notebook for several hours on batteries without being connected to an electrical outlet. Devices that can be set for power conservation under Windows 98 include hard disk drives; monitors and LCD panels; serial, parallel, and USB ports; CD-ROM drives; DVD-ROM drives; PC Card devices; and keyboards, mice, and joysticks.
NOTE: Full power management capabilities are available only on systems that are compliant with the new ACPI specification.
But what if your existing hardware doesn't support ACPI? Table 28.1 outlines what will happen.
| Hardware Type | Legacy OS | Windows 98 |
| Legacy hardware | A legacy OS on legacy hardware does what it always did. | Limited to power support that is supported by the hardware |
| Legacy and ACPI hardware support on the same machine | It works just like a legacy OS on legacy hardware. | During boot-up, Windows 98 tells the hardware to switch from legacy to ACPI mode, and full power management is enabled. |
| ACPI-only hardware management | No power | Full power management |
The Power Management icon in Control Panel lets you set a desired level of power management for your notebook or desktop system. Windows 98 automatically determines what type of power management capabilities your PC has. The Power Management properties sheet, shown in Figure 28.1, then displays a list of devices that can be set for different power conservation levels.
FIG. 28.1 Use the Power Management properties sheet to control the power management settings for your computer.
TIP: Turn off your monitor and hard disks automatically to save power. While on standby, your monitor and hard disk use less power. When you want to use your computer again, it comes out of standby quickly, and your desktop is restored to the exact state in which you left it.
To modify the settings for your PC's power management, use the following procedure:
FIG. 28.2 You can specify power conservation settings in the Power Management properties sheet.
TIP: If you never want a particular device to power down, choose Never in the Turn Off Hard Disks field.
TIP: If you'd like to enable the Power Meter icon in the system tray of the Windows 98 taskbar, put a check next to that option on the Advanced tab of the Power Management properties sheet. Then you can double-click the Power Meter icon in the system tray to open the Power Management properties sheet.
In some cases, you might want to create a new power scheme. For example, when your notebook is docked or using AC power instead of batteries, you'll probably want to use different power management settings than when it's not docked or you're using battery power.
To create a new power scheme, use the following procedure:
FIG. 28.3 You can save your own custom Power Management settings.
Windows 98 also supports a new feature called OnNow that makes your computer more responsive by reducing its startup time. Using power management techniques, OnNow can start your computer in just a few seconds and restore all your programs to the point where you left them. In addition, it allows your computer to continue working even though it appears to be turned off. This means you can leave all your programs running, download your favorite Web pages, send and receive email, back up your hard disk, or tune-up your operating system even when you're not at your computer.
Power management works on computers that support Advanced Power Management (APM), and it works even better on newer computers that support Advanced Configuration and Power Interface (ACPI). Power management also makes it possible for you to put your computer on standby or in hibernation mode to save power resources.
To humans, the PC appears to be either on or off. However, an OnNow PC is actually in one of three states:
NOTE: Another name for OnNow might as well be NeverReallyOff. What appears to be an On/Off switch on the front panel of an OnNow computer really just signals Windows 98 to place all the hardware components of the system into a very low state of power consumption. Look for a hidden "real" power switch on the back of the system.
New Windows 98 PCs that are compliant with the OnNow initiative have the following capa-bilities:
NOTE: Typical wake-up events might include ringing phones or software requests (such as backup routines) that are scheduled to wake up the PC at a predetermined time.
CAUTION: If your applications inadvertently keep the PC busy unnecessarily, your PC will never be able to achieve the full power and noise savings that are possible with OnNow.
© Copyright, Macmillan Computer Publishing. All rights reserved.
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