MI-SUGAR (pronounced "my sugar") is a simple electric circuit design tool that I created in 2003 for macOS (called "Mac OS X" before 2016) after porting the SPICE circuit simulator to Darwin (the Unix-compatible core of macOS) in late 2002. I continued improving MI-SUGAR intensively until early 2004, with only minor changes afterwards. In 2007, I declared MI-SUGAR obsolete and started working on its successor, Volta.

MI-SUGAR was first distributed on the website "MacInit.com", which I created to market my Mac applications. The prefix "MI" is the abbreviation of MacInit while "SUGAR" is a wordplay on "SPICE", the name of the simulation engine.

Misugar macinit logo.png

Misugar logo.png


The user can create analog circuits using the schematic entry tool or the netlist editor, then run the simulation and, finally, inspect the results in the graph plotter. Users can also build their own library of circuit elements.

  • dragging & dropping circuit elements from a rich palette
  • snap-on alignment for easily laying out elements,
  • connecting elements by dragging from the endpoints
  • schematic drawn using vector graphics
  • unlimited undos
  • zooming and panning
  • exporting schematics to SVG
  • converting schematics to SPICE netlists
  • syntax-highlighting in the netlist editor
  • support for creating custom subcircuits
  • ability to run concurrent circuit simulations
  • ability to export results to MATLAB™ or as MathML files
  • plotting simulation results in a window each
  • regional zooming with history in the plotter


Misugar screenshot 1.jpg Misugar screenshot 2.jpg Misugar screenshot 3.jpg Misugar screenshot 4.jpg Misugar screenshot 5.jpg


MI-SUGAR is currently only available as an open-source Xcode project on GitHub. There are no pre-built binaries.

Software Design Issues

The most important issue with the software design of MI-SUGAR is that the device model definitions are hard-coded instead of being loaded from resource files.