Laptop Expansion Cards

Three slot types that look alike

Older laptops have a PC Card slot, a wide slot for Type II cards that use the CardBus interface. Later models replaced it with ExpressCard, narrower at 34 mm or T-shaped at 54 mm, which carries PCIe and USB 2.0 signals. The two are not interchangeable, and many cards here are PCIe-based laptop add-on cards. Modern laptops have neither slot and use M.2 sockets internally instead. Identify the slot in the laptop manual before choosing, because a card that does not match cannot be forced to fit.

What these cards add, and when a USB adapter does the job

The cards here mostly add RS-232 serial ports, from one DB9 port to eight, for configuring network gear or driving industrial and scientific equipment, as well as extra USB ports. Check how many ports it provides, the maximum serial speed, and whether your operating system has a driver for the controller chip. If the laptop has no slot at all, a USB-to-serial adapter or a small USB hub gives similar function without a card. Some cards stick out of the slot, which matters when you carry the laptop.

Questions about Laptop Expansion Cards

How do I tell whether my laptop has PC Card or ExpressCard?

Check the laptop manual or the label next to the slot, which will say PC Card, CardBus or ExpressCard. Width alone can mislead, because PC Card and ExpressCard/54 slots are both 54 mm wide, while ExpressCard/34 slots are narrower.

Can I use an ExpressCard in a PC Card slot?

No. The two slots use different electrical standards and connectors, so a card made for one will not work in the other. Choose the card type that your laptop slot supports.

Will these cards work with a current operating system?

It depends on the controller chip and the maker's driver support. Check the driver page for your Windows or Linux version before relying on a card, especially for older CardBus models.