Programmability is a stable, reversible change in the operating parameters of a cardiac implantable electronic device. The era of non-invasive programming began in 1972, with the development of a dedicated hand-held battery-operated device. Prior to this, there had been crude attempts, involving invasive procedures or a magnet, to change the pacemaker operating parameters. A non-invasive programming system requires an implanted pulse generator and an external programmer, communicating via an energy link. This was initially a pulsed magnetic field allowing opening and closing of a reed switch in the pulse generator in synchrony with the pulses. Soon after, radiofrequency communication was introduced and involved transmission of pulsing on-off radiofrequency bursts, which allowed complex encoding, that recognised the implanted hardware, prevented mis-programming, had security features and confirmed successful programming. As programming became more complex and sophisticated, programmers evolved into desktop models with programming wands and printers. By 1978, multiprogrammable programmers with bidirectional telemetry were introduced and became a driving force in the development of new cardiac implantable technologies and devices.