Printer Plug and Play Installation Requirements

This section outlines the minimum hardware and software requirements for parallel port devices to obtain Plug and Play support under Windows 95. The term Plug and Play is defined here as the ability to attach an I/O device to a host and enable the host to determine that the device has been added, identify it, and either automatically install the necessary device drivers or prompt the user for a diskette containing them.

To offer parallel port Plug and Play capability, the host

Must have a parallel port capable of supporting nibble mode as defined by IEEE-P1284.
May support ECP mode as defined by the IEEE 1284 specification in order to enjoy the improved performance ECP mode provides.

To support Plug and Play, the device connected to the parallel port must offer capabilities in three different areas:

Hardware
Software
Device identification

Device Hardware Capabilities

To participate in Windows 95 Plug and Play, a parallel port device

Must provide a parallel interface which conforms to the IEEE 1284 specification. This interface may be 1284-I compliant (using 1284-A or 1284-B connectors) or 1284-II compliant (using 1284-C connectors).
Must support nibble mode as described in the IEEE 1284 specification.
To receive Microsoft Plug and Play certification, the device must also report the minimal device ID key values as described in IEEE 1284.
May support ECP mode as defined in the IEEE 1284 specification in order to obtain improved performance.

Device Software Capabilities

To participate in Plug and Play, a parallel port device

Must return a device ID string in nibble mode, as defined by the IEEE 1284 specification.

Device Identification Capabilities

To participate in Plug and Play, in general a parallel port device

Must return device ID strings to the host made up of ASCII values between 32 and 127 (between 0x20 and 0x7F), inclusive.
Must provide MANUFACTURER, MODEL, CLASS, and COMPATIBLE ID key values that remain static. Multiple-personality devices are an exception to this, as is described in the section Multiple Emulation Devices.
Must provide MANUFACTURER and MODEL key values that are unique from each manufacturer.

Requirements for reporting device IDs are described in Section 6.6 of the IEEE 1284 specification. Six keys that can be returned by a device are described and these are identified in the following table:

Key	Abbreviation	Comment
MANUFACTURER	MFG	The MFG key value is used in combination with the MDL key value to generate a unique device ID for Plug and Play parallel devices for Windows 95. For more information about this, see the section Generating Unique Plug and Play Device IDs.
COMMAND SET	CMD	This key is ignored by Windows 95 for parallel port devices.
MODEL	MDL	See the comment about the MFG key.
CLASS	CLS	PRINTER is one value this key can have in Windows 95.
DESCRIPTION	DES	The DES key value is a string, up to 128 characters long, that may be presented to the user to describe the device if an INF file cannot be found for the device.
COMPATIBLE ID	CID	The value(s) in this key effectively identifies device drivers that are compatible with the device being identified. If the device is not compatible with another device or the device manufacturer does not want to use a compatible device driver with the device, this key will be empty. For more information, see the section Using CID Values.