PC Cards were introduced in the 1990s for memory expansion on portable computers. They evolved to include various peripheral devices and come in three types. The faster ExpressCard slot has largely replaced PC Cards, with most laptops now using USB ports instead.
A PC Card, formerly a PCMCIA card, is a peripheral interface device used with portable computers that use the card port. Introduced in the early 1990s by the Personal Computer Memory Card International Association (PCMCIA), the slot was originally intended for memory card expansion. As technology evolved, many types of peripheral devices were available in the card format to add functionality to laptops. In 2003 the specification renamed the form factor and port to the ExpressCard slot.
The card is the size of a credit card with added thickness. Form factor varies between devices and as ports evolve. The cards use a 68 pin dual row interface and are either 3.3 volt or 5 volt cards. The 3.3v cards have a protection feature that prevents them from being used in a 5v only port. Some cards can work in 3.3v or 5v mode. The PC Card falls into one of three categories: Type I, Type II, or Type III.
Type I cards operate on a 16-bit interface, are 3mm thick, and were primarily used for RAM or flash memory expansion. A Type I card occupies a single PC Card slot, whereas most laptops of the time featured two slots or ports, one above the other.
Type II cards can be 16-bit or 32-bit and are 5mm thick. These cards provided in-and-out (I/O) support, introducing the ability to add features to the machine that weren’t originally built-in. Modems and network cards are two examples. The Type II card often includes a dongle or short cable with a full-size connector, which was necessary due to the thinness of the card. The connector provides a jack for the necessary equipment, be it a telephone line, an Ethernet cable or other interface.
Other Type II formats include an oversized or thick outer end with the integrated connector(s). While more convenient than a dongle, this form factor can block the secondary port. Even more variants feature retractable antennas and jacks to minimize clutter when the card is not in use and to protect extended parts.
A Type III PC Card can also be 16 or 32 bit and has a thickness of 10.5 mm. These boards can accommodate connectors without the need for a dongle.
When a PC Card is inserted into a machine, the computer searches for the Card Information Structure (CIS) stored on the device. This data reveals the manufacturer, model, card type, power requirements, supported options, and other relevant information. If a machine does not recognize a card, a common reason is that the CIS file is damaged or missing.
The card door made it possible to upgrade a laptop without opening it. If an internal component stopped working or became obsolete, a PC Card was the answer. From wireless modems to mobile broadband, optical mice to TV cards, this interface has kept laptops flexible and expandable.
With the introduction of the faster ExpressCard slot in 2003, the PC Card slot has largely become legacy. By 2007 most laptops came with only the ExpressCard slot or no card slot in response to the growing trend of using USB ports to provide additional functionality. In 2009 PCMCIA disbanded, according to their website, leaving any further development to the USB Implementers Forum (USB-IF).
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