The following is a list of CMOS 4000-series digital logic integrated circuits. In 1968, the original 4000-series was introduced by RCA. Although more recent parts are considerably faster, the 4000 devices operate over a wide power supply range (3V to 18V recommended range for "B" series) and are well suited to unregulated battery powered applications and interfacing with sensitive analogue electronics, where the slower operation may be an EMC advantage. The earlier datasheets included the internal schematics of the gate architectures and a number of novel designs are able to 'mis-use' this additional information to provide semi-analog functions for timing skew and linear signal amplification. Due to the popularity of these parts, other manufacturers released pin-to-pin compatible logic devices and kept the 4000 sequence number as an aid to identification of compatible parts. However, other manufacturers use different prefixes and suffixes on their part numbers, and not all devices are available from all sources or in all package sizes.