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How Windows 98 Works with Hardware

Windows 98 doesn't radically change the way things were handled under Windows 95, but it does include some useful new tools and tweaks. At the center of all hardware, however, is Windows 98's Plug and Play (PnP), the combination of software and hardware that allows the operating system to automatically manage devices.

For PnP to work, your peripherals, system BIOS, and operating system must all incorporate PnP technology. When Windows 98 starts, the operating system and the PC go through a series of steps to establish configurations, arbitrate conflicts, and record changes.

The best place to find the latest 32-bit device drivers for your peripherals is from the vendor. Often, the driver available from a vendor's web site will be more up-to-date than those found on the Windows 98 CD-ROM disc.


These components all come together to eliminate the need for the user to tell each peripheral exactly which resources it can access. IRQ, DMA, and I/O address settings are all assigned by Windows 98 based on the overall picture that PnP provides.

While Windows 98 makes things easier, you need to be knowledgeable about the resources your devices need. This enables you to diagnose and fix simple conflicts without having to resort to time-consuming or costly repair services. IRQs, or interrupt requests, are the most critical of the system resources, if only because nearly all devices need them.

IRQ numbers enable hardware devices to get the CPU's attention. A PC has 14 IRQs, but not all those are actually available to your peripherals. In fact, as PCs incorporate more and more devices, IRQs have become increasingly scarce, which sometimes results in failed installations and conflicts. Table 21.1 lists the IRQs and their most common uses. As you can see, only about a third of these may be available, and often even those are occupied.

Table 21.1 Counting IRQs
IRQ Number Application
2 Cascade from IRQ9
3 Available (or second COM port)
4 COM1, COM3
5 Available (or second printer port, LPT2)
6 Floppy disk controller
7 Printer port (LPT1)
8 System clock
9 Graphics adapter
10 Available
11 Available
12 Mouse (PS/2 systems)
13 Math coprocessor (if applicable)
14 Hard drive controller
15 Available