Digital Clock (Intro)

After having done the project of the digital clock in VHDL, I became very interested in the subject and thought, why not do it the old way? Using TTL and CMOS logic, of the integrated 7400 and 4000 families: decoders, multiplexers, led displays, counters, oscillator crystals, etc. Since it is a long project and that has a lot of information, I will make an entry for each part of the circuit so that the follow-up of the project is not tedious. The chips have come out expensive as it is outdated technology, but nothing can stop the DIY train. Go for it !