TkGate is a digital circuit editor and simulator with a Tcl/Tk based
interface. TkGate includes a large number of built-in devices
including basic gates, memories, ttys and modules for hierarchical
design. The simulator can be controlled either interactively or
through a simulation script. Memory contents can be loaded from
files, and a microcode/macrocode compiler (gmac) is included to create
tkgate memory files from a high-level description. The simulator
supports continous simulation, single step simulation (by clock or
epoch) and breakpoints. Save files are in a Verilog-like format.

TkGate also includes a number of tutorial and example circuits which
can be loaded through the "Help" menu. The examples range from a
simple gate-level 3-bit adder to a 16-bit CPU programmed to play the
"Animals" game.

TkGate has a multi-langauge interface with support for English,
Japanese, French and Spanish.