PCMCIA stands for Personal Computer Memory Card International Association, an international standards body that was established to define, develop and promote the PC card. PCMCIA also stands for 'People Can't Memorize Computer Industry Acronyms,' a play-of-words humor coined because the original acronym and its meaning are difficult to say and remember.

PCMCIA, which consists of some 100 companies and trade associations, publishes the standards for PC Card and ExpressCard that contains the physical, electrical and software specifications for each technology, including the 32-bit CardBus interface of the PC card standard. The group is also responsible for the Expresscard Compliance Program that ensures interoperability of Expresscard products with other products in the market. The current focus of PCMCIA is on mobile applications for modular peripherals in all platforms, improving user experience and creating awareness to expand the market for modular peripherals.

The PC card (formerly called PCMCIA card) and its successor Expresscard are small, credit card-sized devices that were originally designed for memory expansion of laptops where ruggedness, low power, and small size were critical. The scope of the PC card was later expanded to include other devices, such as network cards, modems, hard disks and digital cameras. All PC cards use an identical 68 pin dual row connector and have the same rectangular shape and size - 85.6 by 54 millimeters - but vary in width, depending on the type of card. The original standard was defined for both 5 volt and 3.3 volt cards. PC cards are designed to be hot-swappable, i.e., inserting or removing a card is possible without rebooting the computer.

Card Types

Type I cards are up to 3.3 mm thick and use a 16-bit interface. These are mostly used for memory devices such as RAM, flash memory, one time programmable memory (OTP), and static RAM.

Type II cards are up to 5.5 mm thick and use a 16-bit or 32-bit interface. These cards are often used for modem, network, TV cards and mass storage devices.

Type III cards are up to 10.5 mm thick and use a 16-bit or 32-bit. These are used for external disk drives and other devices with components that cannot fit into Type I and II slots.

Card Slots

Type I slot can hold one Type I card

Type II slot can hold one Type II card or one Type I card

Type III slot can hold one Type III card or a combination of two Type I or II cards.

PC card evolution highlights:

1989 - Establishment of PCMCIA as an alternative to the Japan-made JEIDA memory cards.

1990 - First release of the PCMCIA card standard, with Type I and Type II form factors and the 68-pin connector specifications. The Release 1.0 Standard was designed for memory cards only.

1991 - Merging of PCMCIA with JEIDA. The Release 2.0 Standard that came out after the merging defined the I/O interface and added support for dual voltage memory cards.

1992 - Release 2.01 Standard added some specifications to the 2.0 standard, including the Type III cards and the auto-indexing mass storage for digital imaging.

1995 - Release 5.0 Standard introduced support for low voltage (3.3 Volt) only operation and the 32-bit CardBus interface.

1997 - Release 6.0 Standard introduced specifications for Thermal Ratings System, streamlined PC card configuration and Hot dock/undock support.

1999 - Release 7.0 Standard defined the PC card memory paging, Digital Video Broadcast interface and Windows NT 4.0 Kernel socket services binding

2001 - Release 8.0 Standard defined the CardBay USB Interface

2003 - Release of the Expresscard standard that was designed to replace PC cards.