it was the introduction of full digital fly-by-wire with the A320 in 1988 which enabled this pilot-friendly cockpit to take shape. Fly-by-wire enabled Airbus to establish commonality, making life easier for the pilot.

Thanks to fly-by-wire, the flight decks and handling characteristics of all Airbus aircraft are similar no matter how different in size they are. This makes it easier for pilots to change from one aircraft to another. More importantly, fly-by-wire enhances safety by allowing the programming of the flight protection envelope, which enables pilots to fly the aircraft freely but prevents any abnormal operations such as stalling, flying too fast or overstressing.

http://www.airbus.com/en/airbusfor/pilots/fly-by-wire.html