A PC Card is a credit card sized expansion bus that conforms to PCMCIA standards. PC Cards come in a number of configurations with varying characteristics and functions. You should know the following facts about PC Cards:
- PC Cards can be used by devices like modems, network cards for wired or wireless networks, CD-ROMs, sound cards, SCSI host adapters, IEEE 1394 controllers, USB controllers, and others.
- PC Cards connect to the 16-bit or 32-bit card host I/O bus on the laptop motherboard.
- PC Cards can also be categorized by physical standard, as is illustrated below:
Card Type Description Type I Now obsolete, were typically used for memory (such as SRAM and Flash). Type II Typically used for I/O (such as modem and LAN). Type III Typically used for rotating mass storage (hard drives and optical drives).
- PCMCIA dimensions, excluding thickness, are the same for each type of card and each card type has a 68-pin connector. Thinner cards fit into the thicker ports, but not vice versa. For example, a Type I card will fit into Type II and III ports while a Type III card requires two Type II ports.
- CardBus is a name given to 32-bit PCMCIA cards following the PCMCIA 5.0 or later standards.
The PCMCIA standards are being replaced by a new standard, PCI Express or ExpressCard.
- ExpressCard slots connected directly to the PCIe or USB bus. ExpressCard offers up to 2.5 Gbps on the PCIe bus, or 480 Mbps on the USB bus.
- ExpressCard slots are either 34mm or 54mm wide.
- There are two card form factors:
- ExpressCard/34 are rectangular cards that are 34mm wide. These cards fit into either 34mm or 54mm slots.
- ExpressCard/54 are L shaped cards that are 34mm wide at the connector end, but 54mm wide on the outside edge. These cards fit only into 54mm slots.
- Cards use either PCI Express or USB 2.0 standards (the slot supports both).
- ExpressCards can be used for all types of devices, similar to PCMCIA. An ExpressCard can even be used for a graphics card to attach an external monitor.
- Many newer laptops have ExpressCard slots but not PCMCIA slots. Some laptops have both, while some have neither (assuming that all external devices will connect through the USB ports).