The gEDA project is working on producing a full GPL’d suite of Electronic Design Automation tools. These tools are used for electrical circuit design, schematic capture, simulation, prototyping, and production.
Currently, the gEDA project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout.
gschem is the schematic capture program/tool which is part of gEDA. Its sole purpose is to facilitate the graphical input of components/circuits.
Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate an intermediate form called vvp assembly.
GTKWave is a fully featured GTK+ based waveform viewer. GTKWave is designed to handle many signals at once, it has three signal searching modes (Regular Expressions, Hierarchy, and Tree) as well as the ability to display data in many different formats.