Plug and Play
Each time you boot the system, a series of steps
occur that launch the PnP process. All the hardware on the system is checked
at boot time. If new hardware has been installed, it will be detected and the
appropriate steps will be taken by the PnP system.
The follow list details the steps that Windows
98 goes through during system startup:
- The system BIOS identifies the devices on
the motherboard (including the type of bus), as well as external devices such
as disk drives, keyboard, video display, and other adapter cards that are
required for the boot process.
- The system BIOS determines the resource requirements
(IRQ, DMA, I/O, and memory address) for each boot device. The BIOS also determines
which devices are older devices with fixed resource requirements and which
are PnP devices with flexible resource requirements. Notice that some devices
don't require all four resource types.
- Windows 98 allocates the remaining resources,
after allowing for older resource assignments to each PnP device. If many
older and PnP devices are in use, Windows 98 may have to perform many iterations
of the allocation process, changing the resource assignments of the PnP devices
each time in order to eliminate all resource conflicts.
- Windows 98 creates a final system configuration
and stores the resource allocation data for this configuration in the registration
database (the Registry).
- Windows 98 searches the Windows\System folder
to find the required driver for the device. If the device driver is missing,
a dialog box appears, asking you to insert into drive A the manufacturer's
floppy disk containing the driver software. Windows 98 loads the driver into
memory and then completes its startup operations.
Notice that Windows 98 makes educated guesses
about the identity and resource requirements of older devices. The operating
system features a large database of resource settings for older devices, which
enables it to detect and configure itself to a variety of existing hardware.
However, this detection process is not perfect, and it forces dynamic PnP peripherals
to be configured around the static settings of older hardware.