To ensure that the computer starts in a known state when it is switched on, I need to introduce a method of resetting both the 6502 and the 6522. The 6502 contains a reset pin(40), and the 6522(34), which needs to be held low for a couple of cycles. Placing a switch between this pin and ground is not enough. First, we need to keep the pin high when it is not being pressed. I will achieve this by connecting a 1K resistor between the reset pin and 5V. This will keep the reset pin high but allow it to go low when the button is pressed.
Secondly, I need to consider switch bounce. When a button is pressed, it makes contact multiple times before settling down. To stop this from happening, I need to add a switch debouncer. There are many ways to make a switch debouncer.