ExpressCard

ExpressCard is a modular expansion-card standard for laptops and other portable computers, developed by the PCMCIA consortium and PCI-SIG, and introduced in the early 2000s as a successor to the PC Card/PCMCIA standard. The specification defines two form factors: ExpressCard/34 and ExpressCard/54, named for their widths in millimeters. Both share a common edge connector and are hot-pluggable, allowing users to add peripheral functionality without rebooting.

An ExpressCard module provides either a PCI Express (typically x1) or USB 2.0 interface to the host system, bridged inside the card to present standard devices to the operating system. The host computer must include an ExpressCard slot to use the cards. Cards are designed to be swapped in and out while the system is running and can be used to add networking, mass storage, multimedia, and other capabilities.

Common uses in the field included network adapters (Ethernet and modem), storage interfaces (eSATA or USB-based solutions), FireWire, WLAN, TV tuners, and various specialty peripherals. The format was widely adopted in the mid- to late-2000s on many laptops, docking stations, and some desktop adaptors.

Decline followed the rise of USB 3.0 and Thunderbolt, along with changing laptop designs that dropped ExpressCard slots in favor of integrated interfaces and different expansion ecosystems. By the mid-2010s, ExpressCard support had largely disappeared from new consumer devices. Today it is largely a legacy standard with limited availability in niche markets and legacy hardware.

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