Definition of 4000 series

The 4000 series is the general classification referring to the industry standard integrated circuits which implement a variety of logic functions using CMOS technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of TTL logic chips. Almost all IC manufacturers active during the era fabricated chips from this series. RCA sometimes advertised the line as COSMOS, standing for Complimentary Symmetry Metal Oxide Semiconductor.