Although already used in the 1970s, it took until the mid-1980s before CMOS became the leading edge technology for VLSI circuits. Prior to that time, only a few designs were implemented in CMOS, particularly the ones that really required the low-power features of CMOS. Most examples, then, were battery-supplied applications, such as wristwatches (tens of millions per year), pocket calculators, portable medical devices (hearing aids and implantable heart controls) and remote controls.