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Advanced Power Management and Plug and Play

Battery life and device management are burning issues when you're deciding whether to run Windows NT 4.0 on portables. The decision would be easier if you could get reasonably priced laptops with advanced power management (APM) and Plug-and-Play (PnP) features for NT. Recent developments from Microsoft and other manufacturers make this possibility a reality.

What kinds of APM and PnP features do NT users want in a portable? Table A lists some desirable features the Windows NT Magazine Lab identified in each category. The following paragraphs describe industry solutions to APM and PnP on NT that incorporate advances in hardware (new chipsets and BIOS) and software (core design changes and add-on modules for NT).

Microsoft's Solution­NT 5.0
At the Professional Developers' Conference in October 1996, Microsoft unveiled its solution to APM and PnP on NT: OnNow power management architecture. Microsoft will implement the complete package in NT 5.0, but it plans to release some components as upgrades to NT 4.0.

OnNow addresses desktop, server, and portable power management issues and elements of PnP for the "instantly available PC." OnNow is Microsoft's term for a PC that is always on but can appear to be off. This new technology involves design changes (APIs, Windows Driver Model­WDM, hardware abstraction layer­ HAL, etc.) to both Win95 and NT, and new device drivers, applications, and physical hardware based on the Advanced Configuration and Power Interface (ACPI) specification proposed by Intel, Microsoft, and Toshiba. Let's take a closer look at what you can expect for APM on portables.

Microsoft plans to put the APM functions and policies directly into the OS with full Win32 support to ensure consistent and reliable operation. Applications will be able to access the APM features to control the system. For example, receiving faxes, down- loading from the Internet, synchronizing files, and performing system management can occur while the PC is ostensibly turned off or in standby mode.

OnNow offers new features for NT, such as instant-on (your PC or laptop is ready to use within five seconds, following a suspend mode) and a standby low-power state (the system appears to be off­no disk, fan, display, or other perceptible activity­but it responds to events such as I/O). Figure A shows your system's four power states: mechanical off, soft off, sleeping, and working. Mechanical off means you must flip the power switch to boot up your system. Soft off means that the system appears to be off, but it can boot or restore its previous operating context from a media source such as the disk drive. When the system is sleeping, power consumption is reduced (peripheral devices are off and the processor is idle), but you can wake up the system with an I/O event. When your computer is working, everything functions in a power-conservation mode that depends on system usage (you control the conservation parameters). Applications can alter their behavior based on the power status of the computer (the NT User component tracks application execution states and decides when to sleep). So when you run your portable on battery power, applications can eliminate power-eating tasks such as non-essential background processes, idle loops, and low-priority disk I/O activity.

Figure B shows OnNow's layers and components, how they are embedded in the operating system, and how they relate to the new hardware and interface specifications. The new APM and PnP features require the following upgrades to NT's HAL interfaces:

  • Processor power conservation control
  • Power and clock plane control
  • Timer control
  • Thermal control
  • Battery support
  • System control events generated on the system board (pressing the power button, closing the lid, docking, etc.)
  • System-resume on any wake-up event
  • System indicators control
  • PnP functions such as Get/Set resources and Lock/Eject device

Modifying the HAL makes device-specific power management possible. Each physical device you install in the system­or insert after power-up­maintains its power states, which the OS manages independently while the system runs. Components such as PC Card devices, system drives, and I/O components can concurrently have different power states. Power usage decreases significantly compared to power usage under NT's everything-is-always- on design.

Does Microsoft's solution create a hardware dependency? Yes and no, depending on which and how many functions you want to access. Some capabilities depend on which motherboard and peripherals you run. Full OnNow functionality requires enhancements to PCI, Universal Serial Bus (USB), and IEEE 1394 (firewire) specifications and implementations in future laptops and PCs. Microsoft has rejected BIOS enhancements; however, it will update the Windows NT 4.0 System Agent to support OnNow for nonhardware-specific functions.

What does OnNow mean to NT 4.0 users who don't want to buy new hardware? You'll get some, but not all, power management and PnP features. Some features, such as full-power PnP (the ability to add devices and upgrade the system online), will be hardware dependent. Just about any system should be able to use features such as battery monitoring, screen blanking, and PC Card management under NT 4.0. New user interface (UI) components in the OS will provide access to event scheduling, resource management, properties, and so forth. NT 5.0 is where Microsoft's efforts will come together, so don't expect a full release until fourth quarter 1997. For more information about OnNow, visit

Manufacturer Solutions
IBM and Digital Equipment didn't wait for Microsoft (or anyone else) to solve NT's problems on laptops­they couldn't afford to, with Microsoft dragging its heels on a supplying a solution. Both companies designed machines that implement drivers and libraries for APM and PnP using Microsoft's SDK. At the May 1996 TechEd, Microsoft demonstrated an IBM ThinkPad 760CD (for information about other ThinkPad models, see "IBM ThinkPad 760ED," page 56) running prototypes of APM and PnP features. Later in 1996, Digital announced versions of its Ultra HiNote notebooks that promised full support for APM and PnP (see "Digital Equipment HiNote Ultra II LTS 5150 and HiNote VP 535," page 50). If you are looking for a machine that has APM now, look to IBM and Digital for a true NT 4.0 solution.

Phoenix Technologies' BIOS Solution
Perhaps the best solution for NT 4.0 on portables is the latest creation from Phoenix Technologies: Portables Suite for Windows NT 4.0 (which the company demonstrated in private sessions at Fall Comdex). In a nutshell, the new BIOS is part of the system hardware underneath the HAL, the device drivers for the new functions, and the application layer for new system services and the user interface. The only problem is that few vendors support flash-upgrades of the BIOS (and you can't remove the chips), so you need to buy a new system that uses the new firmware.

Figure C shows the architecture of the new BIOS and its relationship to new software that patches into NT and provides top-layer applications and interfaces. In a nutshell, the suite includes the new BIOS as part of the system hardware beneath the HAL, the device drivers for the new functions, and the application layer for new system services and the user interface.

The product suite includes NoteBIOS, PowerPanel 2.0, BatteryScope 2.0, and PhoenixCard Executive. With the BIOS enhancements, new application components, and additional device drivers, a Phoenix-equipped portable running NT 4.0 will be able to do everything from suspend-to-disk to PC Card management.

The save-to-disk feature will snapshot the system's memory and dump it to disk, so that you can do an instant power-on and pick up where you left off­NoteBIOS will even update the system clock. To lengthen battery life, the Phoenix suite will include intelligent power management for all devices, including disk drives, displays, and PC Cards. You'll be able to manually or automatically power up and power down these components so that they're active only when needed. Finally, you'll be able to hot-swap PC Cards with automatic and dynamic configuration. The new PhoenixCard Executive will even support new technologies such as CardBus (32-bit PC Card) and Zoomed Video.

With the application-level power management components (BatteryScope and PowerPanel), you'll be able to analyze battery performance, monitoring battery health, time remaining, required recharge time, and system status. You'll have almost complete control over system behavior (automatic time-out intervals, events) through PowerPanel, where you can set all your system's APM parameters to suit your needs, or let the software figure it out for you.

TABLE A: APM and PnP Features
Advanced Power Management Plug and Play

Suspend (save memory image to disk)/ resume
Spin down and power drives (hard disk, floppy, CD-ROM)
Power-off unused peripherals, PC Cards, etc.
Blank out screen
Automatic power-off after idle intervals
No-load power-on
Extended battery life (4 hours to 6 hours)
Battery monitoring and intelligent management
Auto-suspend when lid closes
Online (hot) insertion and removal of PC Cards, drives, and other peripherals
Peripherals management

Contact Info
Phoenix Technologies
Digital Equipment
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