The PCMCIA card is a special breed specifically designed for laptop PCs. This card plugs directly into an expansion slot that is accessible from the outside of the laptop. This card is the size of credit card.

The PCMCIA cards come in many different types. The most common include modems, memory cards, hard drives, and network interface cards or NICs.

These cards come in several slot sizes: Type I, Type II, Type III, and Type IV.

Type I cards are designed for memory cards. Type II for anything but hard drives. Type III and IV are designed for hard drives.

The Type IV is backward compatible with Type III and II and I. Type III is backward compatible with Type II and I. Type II is backward compatible with Type I. Most newer laptops today have Type II and III or IV slots.