Computer keyboards tend to have switches in a matrix so that only (columns + rows) number of GPIO pins would be needed on the keyboard controller. Each column g

Computer keyboards tend to have switches in a matrix so that only (columns + rows) number of GPIO pins would be needed on the keyboard controller. Each column gets strobed at once in turn, and the rows sensed. Cherry once made a software/hardware hybrid but it didn't have any advantages compared to software debouncing, and it needed more power, so there was only one model. If I understand it correctly, debouncing with a capacitor delay events somewhat. With software debouncing (done right) you are only required to have a minimum time between the press and release events.