The PC Card multifunction standard specifies that a multifunction device has a set of configuration registers in attribute memory for each function. These registers allow the PCMCIA bus driver to, for example, enable each function independently and define a range of I/O resources that are exclusive to each function. The standard also specifies that a multifunction device contains, in attribute memory, the address of each set of configuration registers. These addresses enable the PCMCIA bus driver to program the configuration registers.

If a 16-bit PC Card device implements the PC Card multifunction standard completely and correctly, the vendor of such a device has minimal INF and driver requirements to ensure that the device is configured properly on an NT-based system. See Supporting PC Cards That Conform to the Multifunction Standard for more information.

If a 16-bit PC Card device does not fully implement the PC Card multifunction standard, the vendor must provide the missing information in an INF file. There are two ways that a multifunction PC Card device might fail to implement the multifunction standard:

1. The device implements a set of multifunction configuration registers per function but does not contain the locations of all sets of registers in its attribute memory.
2. The device does not implement a set of multifunction configuration registers per function.

If a device has the limitations listed above, the PCMCIA bus driver can program the configuration registers if the device's INF has the necessary information in DDInstall.LogConfigOverride section(s). See the following sections for further information:

Cardbus devices essentially follow the PCI multifunction rules. See Supporting Multifunction PCI Devices.