Extending the Power of Hardware Profiles

Does your work often take you out of the office? Do you find yourself working in different settings, such as in a hotel room, on an airplane, or in a client's office? Do you sometimes need a network connection? At other times, do you wish you could turn off your PC Card to extend battery life on your laptop while you're working undocked? With hardware profiles, you can create multiple computer configurations for a specific hardware platform. With the advent of Windows NT on the laptop, Microsoft lets the user tell the operating system (OS) what devices to use on bootup and what devices to ignore.

Hardware profiles can help you get the best performance out of your PC. In September, Michael D. Reilly showed you how to configure hardware profiles for your computer in "Configuring Hardware Profiles." In this article, I will detail more ways to configure devices, help you overcome limited resource allocations, and show you how to configure services with hardware profiles.

Defining Hardware Profiles
Although hardware profiles debuted with Windows 95 as a way to control what device drivers to load, NT takes them a step further. NT hardware profiles let you determine not only what device drivers to load but also what services. Device drivers are the software interface between the OS and the peripheral or hardware. But services are a little more mysterious. In this article, think of services as software components that let the OS perform a specific software task.

Services typically fall into two categories: OS applications and BackOffice and third-party programs. OS applications consist of objects such as kernel virtual device drivers (VxDs) and I/O Manager components such as the Workstation and Server services. When you install BackOffice applications such as Exchange or SQL Server, these programs install applets that are viewable under the Services icon in Control Panel.

With the ability to choose both drivers and services, the user controls what peripherals and programs to start or disable. This situation opens up some interesting scenarios for profiles. For example, laptop PC users can determine whether they will use hardware devices such as the video adapter, network card, or CD-ROM in the docking station or whether they will operate undocked using their laptop peripherals.

Also, laptop users can turn off (and remove) their PC Card to extend battery life while the laptop is undocked. You have no reason to fire up your PC Card if you are working on an electronic spreadsheet while flying over the Atlantic and have no need for your network interface card (NIC) or modem. You can gain 30 minutes to 1 hour of battery up-time.

Administrators can run test configurations of BackOffice applications without installing another instance of NT Server. (Wouldn't you like to install SQL Server, Exchange, and Internet Information Server--IIS--on one instance of NT and not eat up all that hard disk space by installing NT three times?) And, for cards that use the same resources (such as IRQ, I/O ports), you can disable one card and enable the other to reach a stable configuration.

Hardware profiles give you a lot of options. But they also have limitations. Perhaps the biggest limitation is the inability to add different instances of network services such as Domain Name System (DNS), protocols, or clients. For instance, if employees have a hard-coded IP address on their PC configured specifically for their network at their place of employment, they cannot plug their computer into another network across town that has a Dynamic Host Configuration Protocol (DHCP) server configured and expect to automatically become a DHCP client.

Selecting Startup Options
At startup, if you have only one profile, the OS loads that hardware configuration without prompting you. This profile is the one that was saved when you last shut down your computer.

If you've configured multiple profiles, you have other choices at startup. After you select the OS via the boot.ini file, a screen similar to Screen 1 appears asking you to select between the Last Known Good (LKG) configuration or a hardware profile configuration. You can use the up or down arrow to select any hardware profile in the list, or press L to choose the LKG. NT will automatically time out and default to the first profile in the profile list if you don't make a selection.

You can force the system to wait indefinitely for user intervention at this screen or time out to the first hardware profile in the list. To set the timeout, open Control Panel, double-click System, and choose the Hardware Profiles tab shown in Screen 2. From the same window, you can manually edit the order of the profiles list. Select a profile and use the up or down arrow in the dialog box to change the order.