PCMCIA Devices

PCMCIA devices meet the Personal Computer Memory Card International Association standard for the credit card-sized interface cards in portable computers and other small computers. PCMCIA technology supports all Plug and Play functionality. Windows 95 provides automatic installation and drivers for Intel-compatible and Databook-compatible PCMCIA sockets. Windows 95 also supports real-mode and protected-mode PCMCIA system software drivers (card services) from other vendors, but some of the Plug and Play capabilities will not be available, such as hot swapping of network adapters and automatic installation.

Windows 95 supports alternate system configurations for PCMCIA devices, depending on whether the PCMCIA device is docked. The alternate configurations are saved under unique identifiers in the hardware tree to be used for dynamic configuration.

Depending on how the hardware manufacturer uses the Plug and Play standard, a PCMCIA device driver might be combined with an ISA or an EISA driver for the card, or the system's generic driver can be used.

To take advantage of Plug and Play, a card must contain information that Windows 95 can use to create a unique device ID for the card. Device drivers can be implemented under three possible schemes, depending on how complete the Card Information Structure (CIS) is on the card, whether the driver requires memory services, and whether the drive is bus-sensitive:

• A standard Plug and Play device driver for PCMCIA (the preferred driver) can handle dynamic configuration and removal, and receive configuration information from the operating system without knowledge of the card in the PCMCIA bus. The recommended choices are NDIS 3.x drivers for network adapters and Windows NT miniport drivers for SCSI cards, which do not require PCMCIA-specific services such as memory buffers.
• Generic Windows 95 device drivers are supported automatically for devices such as modems and disk drives. If the card contains complete configuration information, the operating system initializes the device and passes configuration information to the driver.
• Manufacturer-supplied drivers are required for device classes such as network or SCSI adapters that require specific PCMCIA functions, such as memory-mapped I/O or memory window operations. Windows 95 supports these operations through the standard card services API.