Advanced Power Management and Plug and Play

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

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

Microsoft's Solution­NT 5.0
At the Professional Developers' Conference in October 1996, Microsoftunveiled 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 releasesome components as upgrades to NT 4.0.

OnNow addresses desktop, server, and portable power management issues andelements of PnP for the "instantly available PC." OnNow is Microsoft'sterm for a PC that is always on but can appear to be off. This new technologyinvolves design changes (APIs, Windows Driver Model­WDM, hardwareabstraction layer­ HAL, etc.) to both Win95 and NT, and new device drivers,applications, and physical hardware based on the Advanced Configuration andPower 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 OSwith full Win32 support to ensure consistent and reliable operation.Applications will be able to access the APM features to control the system. Forexample, receiving faxes, down- loading from the Internet, synchronizing files,and performing system management can occur while the PC is ostensibly turned offor in standby mode.

OnNow offers new features for NT, such as instant-on (your PC or laptop isready to use within five seconds, following a suspend mode) and a standbylow-power state (the system appears to be off­no disk, fan, display, orother perceptible activity­but it responds to events such as I/O). Figure Ashows your system's four power states: mechanical off, soft off, sleeping, andworking. Mechanical off means you must flip the power switch to boot up yoursystem. Soft off means that the system appears to be off, but it can boot orrestore its previous operating context from a media source such as the diskdrive. When the system is sleeping, power consumption is reduced (peripheraldevices are off and the processor is idle), but you can wake up the system withan I/O event. When your computer is working, everything functions in apower-conservation mode that depends on system usage (you control theconservation parameters). Applications can alter their behavior based on thepower status of the computer (the NT User component tracks application executionstates and decides when to sleep). So when you run your portable on batterypower, applications can eliminate power-eating tasks such as non-essentialbackground processes, idle loops, and low-priority disk I/O activity.

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

Modifying the HAL makes device-specific power management possible. Eachphysical device you install in the system­or insert after power-up­maintainsits power states, which the OS manages independently while the system runs.Components such as PC Card devices, system drives, and I/O components canconcurrently have different power states. Power usage decreases significantlycompared 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 capabilitiesdepend on which motherboard and peripherals you run. Full OnNow functionalityrequires 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 NT4.0 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 systemonline), will be hardware dependent. Just about any system should be able to usefeatures such as battery monitoring, screen blanking, and PC Card managementunder NT 4.0. New user interface (UI) components in the OS will provide accessto event scheduling, resource management, properties, and so forth. NT 5.0 iswhere Microsoft's efforts will come together, so don't expect a full releaseuntil fourth quarter 1997. For more information about OnNow, visithttp://www.microsoft.com/hwdev/onnow.htm.

Manufacturer Solutions
IBM and Digital Equipment didn't wait for Microsoft (or anyone else) tosolve NT's problems on laptops­they couldn't afford to, with Microsoftdragging its heels on a supplying a solution. Both companies designed machinesthat implement drivers and libraries for APM and PnP using Microsoft's SDK. Atthe May 1996 TechEd, Microsoft demonstrated an IBM ThinkPad 760CD (forinformation about other ThinkPad models, see "IBM ThinkPad 760ED,"page 56) running prototypes of APM and PnP features. Later in 1996, Digitalannounced versions of its Ultra HiNote notebooks that promised full support forAPM and PnP (see "Digital Equipment HiNote Ultra II LTS 5150 and HiNote VP535," page 50). If you are looking for a machine that has APM now, look toIBM 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 creationfrom Phoenix Technologies: Portables Suite for Windows NT 4.0 (which the companydemonstrated in private sessions at Fall Comdex). In a nutshell, the new BIOS ispart of the system hardware underneath the HAL, the device drivers for the newfunctions, and the application layer for new system services and the userinterface. The only problem is that few vendors support flash-upgrades of theBIOS (and you can't remove the chips), so you need to buy a new system that usesthe new firmware.

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

The product suite includes NoteBIOS, PowerPanel 2.0, BatteryScope 2.0, andPhoenixCard Executive. With the BIOS enhancements, new application components,and additional device drivers, a Phoenix-equipped portable running NT 4.0 willbe 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 todisk, so that you can do an instant power-on and pick up where you left off­NoteBIOSwill even update the system clock. To lengthen battery life, the Phoenix suitewill include intelligent power management for all devices, including diskdrives, displays, and PC Cards. You'll be able to manually or automaticallypower up and power down these components so that they're active only whenneeded. Finally, you'll be able to hot-swap PC Cards with automatic and dynamicconfiguration. The new PhoenixCard Executive will even support new technologiessuch as CardBus (32-bit PC Card) and Zoomed Video.

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