an application for easy building and simulating digital circuits.
http://www.a-rostin.de/klogic/
a graphical user interface which allows users to construct and simulate simple digital circuits.
http://www.cs.mun.ca/~donald/digitcl
TkGate is a event driven digital circuit simulator with a tcl/tk-based graphical editor
http://www.cs.cmu.edu/~hansen/tkgate/
a tool for designing digital circuits & synchronous hardware systems on register-transfer level. The tool comprises all essential building blocks, from simple AND/OR/NOT gates over registers, adders, multipliers, to RAM and ROM memory modules.
http://www.ee.uwa.edu.au/~braunl/retro/
Analog, Digital, Symbolic and Mixed-Mode Circuit Simulation
http://www.tina.com/
for Digital Signal Processors and Microcontrollers
http://signal.ece.utexas.edu/~arifler/wetics/index.html
A Win95+ program for creating timing diagrams for digital circuits f.a. RAM adressing.
http://www.cetest.nl/zips/timediagram.zip
a vertically integrated design tool for specification and synthesis of digital circuits.
http://akebono.stanford.edu/users/cad/synthesis/olympus/