After a foray into digital watches in the 1970s, Girard- Perregaux turned back to analog ones, bringing out multi- function quartz models designed to be as simple and user- friendly as possible, with all the functions set via the crown and only the briefest operating instructions necessary. The crowning moment of this phase arrived in 1986, when G-P unveiled the Equation Espace Perpétuelle, which had perpetual calendar, leap-year and moon-phase displays. Equipped with Caliber 738, the watch had a running autonomy of four to five years so that the wearer seldom needed to reset its calendar functions.