High Quality Content by WIKIPEDIA articles! The Intel MCS-51 (commonly referred to as 8051) is a Harvard architecture, single chip microcontroller (µC) series which was developed by Intel in 1980 for use in embedded systems. Intel`s original versions were popular in the 1980s and early 1990s. While Intel no longer manufactures the MCS-51, binary compatible derivatives remain popular today. In addition to these physical devices, several companies also offer MCS-51 derivatives as IP cores for use in FPGAs or ASICs designs.