4000 Series

The 4000 series is a family of industry standardintegrated circuits (IC) which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor (CMOS) technology, and are still in use today. They were introduced by RCA as CD4000 COS/MOS series 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 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.

4000 series parts have the advantage of lower power consumption, wider range of supply voltages (3 V to 15 V), and simpler circuit design due to the vastly increased fanout. However their slower speed (initially about 1 MHz operation, compared with bipolar TTL's 10 MHz) limits their applications to static or slow speed designs. New fabrication technology has largely overcome the speed problems, while retaining backward compatibility with most circuit designs. Although all semiconductors can be damaged by electrostatic discharge, the high impedance of CMOS inputs makes them more susceptible than bipolar transistor-based, TTL, devices. Eventually, the advantages of CMOS (especially the later series such as 74HC) edged out the older TTL chips, but at the same time ever increasing LSI techniques edged out the modular chip approach to design. The 4000 series is still widely available, but perhaps less important than it was two decades ago.

The series was extended in the late 1970s and 1980s to include new types which implemented new functions, or were better versions of existing chips in the 4000 series. Most of these newer chips were given 45xx and 45xxx designations, but are usually still regarded by engineers as part of the 4000 series.

In the 1990s, some manufacturers (e.g. Texas Instruments) ported the 4000 series to their newer HCMOS technology with devices such as the 74HCT4060 providing equivalent functionality to a 4060 IC but with greater speed.

The 4000 series integrated circuits have been used in space satellites for many decades.