On January 7, 2003, Apple Computer introduced AirPort Extreme, based on the 802.11g specification. AirPort Extreme allows data transfer of up to 54 Mbit/s, and is fully backwards-compatible with the thousands of existing 802.11b (AirPort) base stations in coffee shops, retail stores, offices and homes. All of Apple's current computer models, with the exception of the XServe, have a slot to insert an AirPort Extreme card, and all models of PowerBook and iBook now ship with a card as standard. The Extreme cards, however, do not work in older Macs -- the Airport bus cannot support the new faster transfer rate. However, an Airport Extreme base station can communicate both with newer 802.11g-based devices and the older 802.11b AirPort cards.
The AirPort Extreme runs on an AMD Alchemy Au1500 processor which is based on the MIPS architecture. The original AirPort cards used Lucent's chipset, but unlike the Lucent WaveLan Silver Card (the equivalent 40-bit card from Lucent) Apple released a firmware update to raise the encryption level to 128-bit (effectively giving a free upgrade to a Lucent WaveLan Gold card) in 2001.
The AirPort Extreme base station also introduced the concept of a USB device connected to the base station (e.g., a printer) -- so as to, for example, enable wireless printing. At first trivial, it soon grew in importance. It soon became commonplace; the AirPort Express includes the feature as well.