Personal Computer Memory Card International Association (PCMCIAis an international standards body and trade association founded in 1989 to establish standards for Integrated Circuit cards and to promote interchangeability among mobile computers where ruggedness, low power, and small size were critical. PCMCIA has developed a standard for small PC Cards, which is called PCMCIA Card. The PCMCIA PC Card can be used with many computer types regardless of microprocessor type. They are also suitable for use in other digital applications such as test equipment, digital imaging equipment and industrial controllers.

There are in fact three types of PCMCIA cards. All three have the same rectangular size (85.6 by 54 millimeters), but different widths

• Type I cards can be up to 3.3 mm thick, and are used primarily for adding additional ROM or RAM to a computer.
• Type II cards can be up to 5.5 mm thick. These cards are often used for modem and fax modem cards.
• Type III cards can be up to 10.5 mm thick, which is sufficiently large for portable disk drives.

The PCMCIA standard has evolved over time. Release 1.0 was the original release and established standards aimed at memory cards modeled after existing RAM cards. Release 2.0 - 2.1 included Card and Socket Services software specifications, ATA, and AIMS specifications. (ATA stands for AT Attachment and refers to the IDE drive interface on a PC Card. AIMS stands for Auto Indexing Mass Storage. AIMS is the standard for storing image and multimedia data on a PC Card and is used typically for camera applications.) The latest release, PC Card Specification - February 1995, includes enhancements for DMA (Direct Memory Access), multi-media at higher speeds, plug and play concepts, multi-function cards, and CardBus. With each release of the PCMCIA standard, efforts have been made to maintain backward compatibility with PC Cards designed to earlier releases of the standard.

Features of PC Card Technology

• Card Information Structure> - The CIS describes the characteristics and capabilities of the card so the host system can automatically configure it.
• CardBus - CardBus allows PC Cards and hosts to use 32-bit busmastering and to operate at speeds up to 33MHz.
• DMA - The Standard allows cards to utilize Direct Memory Access technology directly in the hardware when matched with a corresponding host system.
• eXecute In Place (XIP) - Allows operating system and application software to run directly from the PC Card, eliminating the need for large amounts of system RAM.
• Low Voltage Operation - The Standard enables 3.3 and 5 volt operation.
• Multiple Function PC Cards - The Standard enables truly standardized multiple function PC-Cards.
• Plug and Play - PC Cards can be inserted or removed while the system is on because power and ground contact pins are the longest contacts, ensuring that disconnect signals disengage first, preserving data integrity.
• Power Management - The Standard provides a means to interface to APM (Advanced Power Management) through the Card Services Specification.
• Zoomed Video (ZV) - Zoomed Video is a connection between a PC Card and host system that allows the card to write video data directly to the VGA controller.

PCMCIA Card: A PC Card by Personal Computer Memory Card International Association

Related Terms: PC card, Plug an Play

Reference Links: http://www.pcmcia.org: The Official PCMCIA Site