TkGate is a event driven digital circuit simulator
with a tcl/tk-based graphical editor.
TkGate supports a wide range of primitive circuit
elements as well as user-defined modules for
hierarchical design.
The distribution comes with a number of tutorial and
example circuits which can be loaded through the
"Help" menu.
The example circuits include a simple CPU, programmed
to run the Animals game.
TkGate is free software provided with source code
under the Gnu Public License.