With the PCMCIA Expansion Module for the PowerBook 500 series, you can use modem cards that conform to the PCMCIA 2.1 standard and flash cards and hard disk cards that conform to the ATA standard.

PCMCIA on other PowerBook models offer full Card and Socket Services support. This means that any 3rd party developer can modify their software drivers to make their cards available on the Macintosh. Card and Socket Services is part of the PCMCIA industry standard.