Formerly called PCMCIA cards, the PC card used a 68-pin, dual-row connecting interface and is about the size of a credit card. It varies in thickness from 0.13 to 0.64 inches, and was originally built around an enhanced 16-bit Industry Standard Architecture bus platform.

PC cards come in five types:

• Type I Cards: Designed to the original specifications. They featured a 16-bit interface and were typically used for memory devices such as RAM, flash memory, one-time programmable memory and static random access memory cards.
• Type II Cards: Featured a 16-bit or 32-bit interface. These cards introduced input/output support, which allowed the attachment of a variety of peripherals directly or via a short cable.
• Type III Cards: These were also 16-bit or 32-bit, and they accommodated a hard disk drive and other interface cards with full-sized connectors.
• Type IV Cards: Introduced by Toshiba, they have not been officially standardized or sanctioned by the PCMCIA.
• Compact Flash Cards: Smaller cards that feature a 50-pin PC card interface with both a memory mode and an ATA storage interface mode. These are commonly used in modern single-lens reflex digital cameras and other devices.

Today, nearly all the functions the PC card interface was designed for are powered by USB devices. The ExpressCard, which replaced the PC Card, has a USB interface.