Plug and Play BIOS

The term Legacy Plug and Play, also shortened to PnP, describes a series of specifications and Microsoft Windows features geared towards operating system configuration of devices. The standards were primarily aimed at the IBM PC standard bus, later dubbed Industry Standard Architecture (ISA). Related specifications are also defined for the common external or specialist busses commonly attached via ISA at the time of development, including RS-232 and parallel port devices.

As a Windows feature, Plug and Play refers to operating system functionality that supports connectivity, configuration and management with native plug and play devices. Originally considered part of the same feature set as the specifications, Plug and Play in this context refers primarily to the responsibilities and interfaces associated with Windows driver development.

Plug and Play allows for detection of devices without user intervention, and occasionally for minor configuration of device resources, such as I/O ports and device memory maps. PnP is a specific set of standards, not be confused with the generic term plug and play, which describes any hardware specification that alleviates the need for user configuration of device resources.

The Plug and Play standard requires configuration of devices to be handled by system firmware, which then provides details of resources allocations to the operating system. The process is invoked at boot time. When the computer is first turned on, compatible devices are identified and assigned non-conflicting addresses and interrupt request numbers.

The term was adopted by Microsoft in reference to their Windows 95 product. Other operating systems, such as AmigaOS and the Mac OS NuBus system, had already supported such features for some time (under various names, or no name). Even Yggdrasil Linux advertised itself as "Plug and Play Linux" at least 2 years before Windows 95. But the term plug and play gradually became universal due to worldwide acceptance of Windows.

...
Wikipedia