In computing, the jiffy is the duration of one tick of the system timer interrupt. Typically, this time is 0.01 seconds, though in some earlier systems (such as the Commodore 8-bit machines) the jiffy was defined as 1 ⁄ 60 of a second, roughly equal to the vertical refresh period (i.e. the field rate) on NTSC video hardware (and the period of AC electric power in North America).