Plug and Play BIOS Specification

Plug and Play BIOS Specification 1.0A Page 5
This is the key consideration in a system BIOS. It is considered unacceptable to change the
architecture of a System BIOS to prevent the thousands of ISA cards and software programs that
rely on the system BIOS for services.
Eliminate resource conflicts during the POST procedure
A common problem that plagues many ISA systems today is the fact that there are a lot more
devices available than there are system resources. In this environment, devices are bound to have
conflicting resources. The system BIOS will now play a key role to help prevent these resource
conflicts by not enabling devices which conflict with the primary boot devices, and relocating boot
devices, if necessary, to allow a successful load of the operating system. It is the role of the
operating system to provide support for communicating irreconcilable resource conflicts to the
user.
Support Plug and Play ISA cards
A Plug and Play system BIOS is responsible for the isolation, enumeration, and optional
configuration of Plug and Play ISA cards. These cards, which provide information on their
resource requirements and permit software to configure those resources, will allow the system
BIOS to arrive at a conflict free configuration necessary to load the operating system.
Allow dynamic configuration of systemboard devices
Systemboard devices have traditionally been treated as having somewhat static configurations. It is
a goal of the Plug and Play BIOS specification to provide a standard mechanism whereby
systemboard devices may be configured dynamically by system software. This will grant
configuration management software a great deal of flexibility when system resources are in
demand and alternate configurations are necessary.
Note: Dynamic device configuration requires explicit device driver support.
Provide system event notification
The system BIOS is capable of detecting certain hardware events that could affect the system
configuration. By providing an event notification mechanism, an operating system can recognize
the event and process any necessary configuration changes.