Plug and Play Support in Windows 95

Plug and Play is an independent set of computer architecture specifications that hardware manufacturers use to produce computer devices that can be configured with no user intervention.

For Plug and Play-compliant devices, installation consists of plugging in the device and turning on the computer. For example, a user can do the following:

Insert and remove Plug and Play-compliant devices such as PCMCIA cards with automatic configuration.
Connect to a docking station or network without restarting the computer or changing configuration parameters.
Add a new monitor by plugging it in and turning it on.

The Plug and Play capabilities in Windows 95 have been widely described as key benefits to moving to Windows 95, because of the related reduction in hardware and software support costs. When Windows 95 detects the presence of a Plug and Play-compliant device, its device driver can be loaded and configured dynamically, requiring little or no user input. After the device and driver are installed, the driver reacts to system messages when a device is inserted or removed.

Microsoft recommends adding Plug and Play-compliant devices on legacy computers rather than adding non-Plug and Play devices. To use all Plug and Play features, however, your system must include a Plug and Play BIOS (the motherboard), devices (buses), and an operating system (Windows 95).

The following describes Plug and Play requirements and benefits.

The following table compares the Plug and Play implementation in the Windows 95 operating system against other implementations.

Windows 95 Plug and Play	Most other implementations
Dynamically loads, initializes, and unloads drivers in protected mode.	Run in real mode, with MS-DOS – based drivers loaded in CONFIG.SYS.
Supports a wide range of device types (as described in the following section).	Include only basic PCI-based and ISA-based device configuration.
Provides robust detection for devices, which is critical for Plug and Play on legacy computers.	Do not provide hardware detection.
Notifies other drivers and applications when a new device is available for use. Windows 95 also includes an automatic installation procedure to ensure that appropriate drivers are installed and loaded.	Configure device IRQ settings and so on, but the burden of installation falls on the user.
Provides robust, seamless operation through the integration of all subsystems and the startup process.	Might not be as reliable.
Provides an architecture with a consistent driver and bus interface for all devices.	In real mode, do not provide a supporting architecture.