 Much expansion that formerly required a PCMCIA card is catered for by USB, reducing the requirement for internal expansion slots; by 2011 many laptops had none

ExpressCard and CardBus sockets are physically and electrically incompatible.ExpressCard-to-CardBus and Cardbus-to-ExpressCard adapters are available that connect a Cardbus card to an Expresscard slot, or vice versa, and carry out the required electrical interfacing.These adapters do not handle older non-Cardbus PCMCIA cards.