Programmable Circuitry

image: Altera
Programmable circuits (blue lines) in a field-programmable gate array (FPGA) can be created or removed by sending electronic signals to gates in the logic elements. A built-in grid of circuits arranged in columns and rows allows the designer to connect a logic element to other logic elements or to an external memory or microprocessor. The logic elements are grouped in blocks that perform basic binary operations such as AND, OR and NOT; several firms, including Xilinx and Altera, have developed devices with the capability of 100,000 equivalent gates.

--J. V. and W. H. M. S.