A logic IC is a semiconductor device that performs basic logic operations on one or more digital input signals to produce a digital output signal, which is able to handle very complex control and arithmetic problems.
Logic ICs can be mainly divided into two categories: fixed logic devices and programmable logic devices. As the name suggests, circuits in fixed logic devices are permanent, which perform a function or set of functions that cannot be changed once manufactured. Programmable logic devices, on the other hand, are standard off-the-shelf parts that offer customers a wide variety of logic capabilities, features, speeds and voltage characteristics. Such devices can be changed at any time to perform different functions.
The two main types of programmable logic devices are Field Programmable Gate Arrays (FPGAs) and Complex Programmable Logic Devices (CPLDs). Of these two types, FPGAs offer the highest logic density, richest features, and highest performance. The latest FPGA devices, such as some in the Xilinx Virtex family, offer eight million system gates.