As you might guess from the name, the clock uses CMOS logic, based around a 12 bit counter, to provide the divider circuits 24 (daily) and 60 (minutes and seconds).

Engineers choose CMOS/biCMOS logic to be “green” and reduce power consumption. CMOS and biCMOS only draw power on transitions, so those circuits run cool at slow speeds. So why is the board hot?

Here we demonstrate that a significant reduction in the use of field-effect transistors can be achieved by constructing carbon nanotube-based integrated circuits based on a pass-transistor logic ...

Any typical digital design style with CMOS uses complementary pairs of p-type and n-type MOSFETs for logic functions implementation. Naturally, CMOS always ought to provide INVERTED outputs like ...