Complex Programmable Logic Devices - CPLDs

A Complex Programmable Logic Device (CPLD) is an IC that can be configured to perform arbitrary logic functions.  They are usually configured through a special set of access pins called a JTAG port, named after the Joint Test Action Group, which defined the protocol, but programming methods are proprietary and may vary by manufacturer.  A CPLD is non-volatile, meaning that the programmed state is retained even if power is removed.  CPLDs are available that have more than one hundred IO pins and tens of thousands of programmable elements.