This applet needs Java version 1.2 or greater to run. Go to java.com to update your browser plugin.
If you are running Netscape 4.x, I'm not sure how to intall a new java plugin.
If all else fails, install a Java Deveoplemt Kit (JDK/SDK) and run:
$ appletviewer http://ups.physics.wisc.edu/~hal/SSL/2003/rotor-router-v0.4/
| Key | Action |
|---|---|
| '+' or '=' | Speed up the applet. |
| '-' | Slow down. |
| Ctrl+Shift+'R' | Restart |
| spacebar | pause |
The program will drop a grain of sand at the center cell in the n X n grid. Initially all the cells are pointed in the left direction. Everytime a grain of sand touches a cell the arrow the cell is pointing rotates clockwise. Grains of sand are routed via the direction of the cell arrow. Note that the arrow changes direction first then a grain of sand is routed. The arrow on a cell represents the direction that the last grain went when it left the cell. A grain of sand moves until it finds a empty cell.
What do the colors mean:
If a cell is empty is has the color white.
If a cell is occupied and the arrow is pointing left, it has the color yellow.
If a cell is occupied and the arrow is pointing down, it has the color green.
If a cell is occupied and the arrow is pointing right, it has the color blueish.
If a cell is occupied and the arrow is pointing up, it has the color red.
Colors are updated after a grain of sand has moved into an unoccupied cell.