PC Hardware —

Computer Cards (PCMCIA)

To provide laptop and notebook computers with the same expandability associated with desktop computers, the Personal Computer Memory Card International Association (PCMCIA) established several standards for credit-card-sized expansion boards that fit into small slots on these smaller machines. PCMCIA is also referred to as the PC Card bus. The PCMCIA standards have revolutionized mobile personal computers, providing them with the ability to add memory expansion cards, SCSI devices, communication hardware (for instance, modems and faxes) and many other devices that were previously unavailable to laptop and notebook computer users.

Compatibility problems surfaced along with the development of the PCMCIA card for portable computers. To overcome these incompatibilities, PCMCIA standards were created. The following table outlines the four PCMCIA types and their guidelines.

PCMCIA types and their guidelines

Type I

This original computer-card standard is now referred to as the Type I standard. These slots work only with memory expansion cards. Type I cards are 3.3 mm thick.

Type II

Type II cards support most types of expansion devices (like communication hardware) or network adapters. Type II can accommodate cards that are 5 mm thick.

Type III

Type III slots are primarily for computers with removable hard disk drives. This standard was introduced in 1992. They are 10.5 mm thick; however, they are compatible with Type I and Type II cards.

Type IV

Type IV slots are intended to be used with hard disk drives that are thicker than the 10.5 mm Type III slot.

The PC Card itself is usually sealed in a thin metal case. One end contains the interface to the PCMCIA adapter (68 tiny pinholes); the other end might contain a connector for a telephone line, a network, or another external device.

PCMCIA (PC Card) is part of the Plug and Play standardwhich means it allows you to add components without first shutting off or rebooting the computer. In short, PCMCIA buses are not configured with jumper settings (because they don't have any) but with software.