Hardware Reference
In-Depth Information
• PnP hardware
• PnP BIOS
• PnP OS
Each of these components needs to be PnP compatible, meaning that it complies with the
PnP specifications. Of course, support for these features is found in all modern systems.
The Hardware Component
The
hardware component
refers to both computer systems and adapter cards. PnP adapter
cards communicate with the system BIOS and the OS to convey information about which
system resources are necessary. The BIOS and OS, in turn, resolve conflicts (wherever
possible) and inform the adapter card which specific resources it should use. The adapter
card then can modify its configuration to use the specified resources.
The BIOS Component
The BIOS component means that any systems built in 1996 or earlier need BIOS updates
to support PnP. Newer systems have PnP BIOSes. For a BIOS to be compatible, it must
support 13 additional system function calls, which can be used by the OS component of
a PnP system. The PnP BIOS specification was developed jointly by Compaq, Intel, and
Phoenix Technologies.
The PnP features of the BIOS are implemented through an expanded POST. The BIOS is
responsible for identification, isolation, and possible configuration of PnP adapter cards.
The BIOS accomplishes these tasks by performing the following steps:
1.
Disables any configurable devices on the motherboard or on adapter cards
2.
Identifies any PnP PCI or ISA devices
3.
Compiles an initial resource-allocation map for ports, IRQs, DMAs, and memory
4.
Enables I/O devices
5.
Scans the ROMs of ISA devices
6.
Configuresinitialprogram-load(IPL)devices,whichareusedlatertobootthesystem
7.
Enables configurable devices by informing them which resources have been assigned
to them
8.
Starts the bootstrap loader
9.
Transfers control to the OS
