Field-programmable gate array

A Field-Programmable Gate Array (FPGA) is a general purpose logic matrix configurable integrated circuit. It consists of a collection of logic gates that can be connected together in an almost unlimited number of combinations to produce custom operations that would normally only be possible with full-custom integrated circuits. Since FPGAs are produced in high volume, they can bring economies of scale to one-off and low volume projects.

Several open hardware projects use FPGAs, such as
 * Minimig FPGA
 * Balloon Xscale + FPGA board
 * The Open Graphics Project (OGP) is developing graphics cards with fully published specs and open source drivers. Since the first version will be a FPGA, is also collecting information on FPGA programming and interfacing.
 * ... (Add other open hardware projects I'm forgetting to this list)
 * ... (Add other open hardware projects I'm forgetting to this list)
 * ... (Add other open hardware projects I'm forgetting to this list)

Verilog ... Xilinx ... Altera ... Lattice ...

Verilog
Verilog is a hardware description language (HDL) used to model electronic systems. The language (sometimes called Verilog HDL) supports the design, verification, and implementation of analog, digital, and mixed-signal circuits at various levels of abstraction.

VHDL
VHDL (VHSIC hardware description language) is commonly used as a design-entry language for designing digital circuits as field-programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs).