We place a single point. Eight small decisions determine what happens in the row below. Then we apply those same decisions again and again.
Read from top to bottom
The first row is the starting state. Each new row is computed from the previous one. A cell’s next state depends on a neighbourhood of three: its left neighbour, itself and its right neighbour. In this implementation, the left and right edges connect.
Three cells, each on or off, give eight possible neighbourhoods. The eight buttons above choose whether the next cell is on in each case. Read those eight decisions as a binary number and you get a rule number from 0 to 255.
A small comparison
With One point selected, try 90, then 30. The starting point stays the same while the whole image changes. Return to 90 and toggle just one decision button. The three small squares show which local neighbourhood you changed.
Now keep the rule and choose Three points. Watch what happens where the patterns meet. The scattered start uses the same sequence every time, so you can compare rules on common ground.
Time in this picture
TRACE computes 96 rows, each 129 cells wide: the starting state followed by 95 steps. The whole history is visible at once. There is no animation to wait for; changing a setting recomputes the picture.
A rule number is a short name for its decisions, not a quality score. Try extremes such as 0 or 255 too. Sometimes the quietest image makes it easiest to see how eight local decisions become a picture.
Take it with you
Save pattern prepares the current image as a PNG. The filename records the rule and the starting state, so you can recreate it. There is also a note on the names we give patterns in the field book.