4000 series

The 4000 series is a family of industry-standard integrated circuits (ICs) which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor (CMOS) technology, which were introduced in 1968 and are still in use today. Almost all IC manufacturers active during the era fabricated chips from this series. RCA sometimes advertised the line as COSMOS, standing for COmplementary Symmetry Metal-Oxide Semiconductor. The naming system followed the RCA convention of CA for analog, CD for digital, but did not relate to the Texas Instruments SN7400 series numbering scheme.