TOYfdtd1 is a stripped-down minimalist, 3D fdtd code demonstrating the basic tasks in implementing a simple 3D fdtd simulation. An idealized rectangular waveguide is modeled by treating the interior of the mesh as free space and enforcing PEC conditions on the faces of the mesh. A simplified plane wave source is inserted at one end. First released 12 April 1999. Version 1.03 released 2 December 1999.