Computers are one of the fastest changing technologies in our society. Not only is the hardware and software changing at the desktop, but the "information superhighway," the Internet, the World Wide Web, and other such emerging information systems offer new uses for computers and information technologies that are changing our lives. The systems of tomorrow may drastically differ from those we see on our desktops today. Much of what has been discussed in earlier chapters could be out of date or obsolete in a few years. We encourage forward-thinking readers to familiarize themselves with the emerging approaches and trends in power management that will likely be prominent features of PC systems available in the near future.

Although the trend in computer displays is toward larger, high-resolution, color monitors, there are several important emerging monitor technologies that offer some relief in the historical increase in power. Most of today's monitors are Cathode Ray Tubes (CRTs). The two technologies that show promise in gaining significant market share in the near future are Liquid Crystal Display technologies, and thin CRTs. These new technologies use less than 30 W when fully active.

Flat-panel displays used with today's laptop computers use far less power than CRTs, but currently their high cost limits their use with desktop PCs. This is changing as manufacturers seek to bring costs down and build larger displays. Color LCDs are likely to increase their share of the monitor market. One manufacturer offers a 23 W, 10 inch LCD for use with desktop computers. LCDs can also be powered up and down more rapidly than most CRTs.

A new thin CRT is under development to compete in the flat-panel display market. Developers are hoping to provide them at lower costs than LCDs. Thin CRTs are based on the same tube technology that is used in standard desktop monitors, but use a thin flat tube instead of the traditional bell shaped tube Thin CRTs are reported to use only about 2 W for a standard monitor.

While this guide is focused on power management for PCs for periods when they are not fully active, there are also opportunities to reduce active power. Active power can be lowered with techniques such as reducing the chip count through more integration of functions, lowering the power supply voltage, using a more efficient power supply, or switching to smaller (less energy-intensive) expansion cards.

Power management in PCs is migrating upwards from the BIOS to the software operating level. This evolution is apparent in both Microsoft's OnNow® initiative, and in IBM's proposed architecture for power management with future PowerPC® systems which are discussed below.

OnNow represents Microsoft's plans for the future of power management, where the PC stays on continuously and power-manages connected peripherals. It is a comprehensive approach to power management that allows all devices and all applications to use their power management features. The goal is the make this transparent and simple for end users. Microsoft is particularly interested in developing these features for home computers which they believe require instant accessibility. They are also interested in integrating the features into all PCs, whether they are portables, desktops, or servers.

Microsoft states that (Microsoft, 1996):

"The OnNow PC platform will be expected to function in these ways:

• The PC is ready to use immediately when the user presses the On button
• The PC is perceived to be off when not in use but is still capable of responding to wake-up events. Wake-up events might be triggered by a device receiving input such as a phone ringing, or by software that has requested the PC to wake at some predetermined time.
• Software adjusts its behavior when the PC's power mode changes. The operating system and applications work together intelligently to operate the PC to deliver effective power management in accordance with the user's current needs and expectations. For example, applications will not inadvertently keep the PC busy when it is not necessary, and instead will pro-actively participate in shutting down the PC to conserve energy and reduce noise."

For any of this to work, component manufacturers need to build systems and peripherals that can communicate power management information with the PC. There will be a transition period during which design changes are needed for related systems and peripherals as well as for software. OnNow defines a standard interface for power managing PC peripherals such as CD-ROMs, network cards, hard-disk drives, and printers, as well as entertainment and consumer electronics. Over time, Microsoft hopes that the proliferation of OnNow-capable systems (running either Microsoft's or other operating systems) will make a major contribution to conserving energy, in line with the goals of the EPA's Energy Star and related programs. Microsoft believes that OnNow represents a paradigm shift.

As part of OnNow, Microsoft, Intel and Toshiba are also defining a new specification called The Advanced Configuration and Power Interface (ACPI, 1996). The ACPI specification provides for the operating system to direct power management operation. ACPI is expected to be implemented on all classes of computers, including desktop, mobile, home and server machines.

A related evolution in power management technology has been proposed by IBM with the PowerPC platform (Rawson, 1995). IBM has developed a specific architecture, methodology, and system of terminology for power management to work with both hardware and software (though it parallels APM in many respects). They suggest that power management can only be optimized by taking advantage of synergy between the operating system power management facilities and power-management-aware application software. Rawson summarizes:

"The user will benefit as the reserve computational capacity of systems increase while at the same time the average power requirements decrease. Ultimately the environment benefits as well. Reaching this goal, however, requires cooperation of component manufacturers, system hardware designers, operating system providers, and application software developers."

The sections above focused primarily on power management in stand-alone PCs. As described in Section 3.4, energy savings in networks is more complex than in stand-alone equipment. A Swiss research project and an emerging network controller technology from the computer industry demonstrate new concepts for power management at the network level.

In an effort to evaluate the feasibility for efficient energy management at the network level, a small client-server network was developed to test a prototype energy management device (Bachmann and Brüniger, 1996). The device consumed less than one Watt, and is being prepared for commercialization. The device reduced the energy use of the server computer (with two, 2 GB hard drives) and central equipment (a monitor, digital audio tape system, and CD-ROM reader) by fifty percent for three months during the test period.

While this last example described energy savings on a server system, this next example emphasizes network-level power management. Hewlett-Packard (HP) and Advanced Micro Devices (AMD) co-developed a new protocol (and chipset) called Magic Packet™. According to AMD:

"The Magic Packet™ technology is used to remotely wake up a sleeping PC on a network. This is accomplished by sending a specific packet of information called a Magic Packet frame, to a node on the network. When a PC capable of receiving the specific frame goes to sleep, it will enable the Magic Packet mode in the LAN controller, and when the LAN controller receives a Magic Packet frame, it will alert the system to wake up. The Magic Packet technology is designed to be implemented entirely in the LAN Controller."

This relatively new technology is being shipped in some current PCs and other manufacturers are expected to follow suit. HP extended the the technology to allow remote powering up from an off mode.

It is clear that the evolution of power management brings increasing complexity, and potentially includes more effective techniques to mitigate future increases in energy requirements for computers and monitors. One important issue in this evolution is that it will require re-evaluating our current methods for describing the energy efficiency or performance of a PC. Simply stating whether or not it can meet a 30 W low-power target will not adequately characterize the power-management features. Thus, it is likely that there will be new methods to convey this information to consumers, allowing them to evaluate energy saving features.

The emerging power-management technologies described in the previous section will also migrate into larger workstations and servers, including unix-based systems. This evolution also illustrates the need for new metrics for higher-end computers. Discussions are underway with several manufacturers to develop a version of the Energy Star Computers program for larger computers.

Continue to Chapter 7: Summary.

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