Now we will cover multiple key presses. Let's say that both keys A and D are pressed at the same time. The matrix will look like this:
Figure 9. The A and D Keys are Pressed
Both nodes C1R1 and C2R2 should be detected. Here is the circuit with both switches A and D closed:
Figure 10. The A and D Switches are Closed
Scanning column C1 then column C2 produces an outcome like this:
Figure 11. Row 1 is Activated
Figure 12. Row 2 is Activated
When column C1 is activated, row R1 is active, hence node C1R1 is activated. When column C2 is activated, row R2 is activated, hence node C2R2 is activated.