The blue lines are the columns and the red lines the rows. There are 16 knots that the rows and columns intersect. The columns and the rows are NOT in contact! Suppose that we want to make a key matrix. To do this, we will have to connect a button to each knot. The buttons will have a push-to-make contact. When the operator pushes this button, it will connect the column and the row that it corresponds to. Now i will put the push-to-make buttons onto the matrix