RealTek's 802.11b chipset is the rtl8180. It is used in some cardbus, PCI, and min-PCI cards. There is no firmware, so most functionality is handled by the driver.
A binary Linux driver was produced, but that has not been updated since 2.4.20.
A reverse engineered driver was been written by Andrea Merello: http://rtl8180-sa2400.sourceforge.net/
Initially, only the Phillips sa2400 radio was supported, but support for the Maxim max2820 and GCT grf5101 radios has been added. The website has a substantial list of cards known to work. While not complete, the driver provides most functionality.
