Serial resistors in matrix keypads are used to prevent ghosting. Ghosting is when a key is pressed and then released, but the button remains depressed and input continues to be registered. This can result in incorrect input being registered if more than one key is pressed at the same time. The presence of serial resistors helps to ensure that only one key will be registered at a time, by preventing current from flowing through the other keys when they are not being pressed. This results in a more accurate input and eliminates the risk of incorrect...