Occam: A primary parallel programming language

In this paper, we are going to return to early parallel programming language Occam and investigate its features, hardware, concepts, versions and concurrency. Due to this, we will begin with the development history of this program. Then, the Transputer as the hardware that Occam is using it will be investigated as pioneering microprocessor architecture of the 1980s, featuring integrated memory and serial communication links, intended for parallel computing. Different versions of Occam including Occam 1, Occam 2, Occam 2.1 and Occam ? are going to be talked in follow. Characteristics and features on these versions are talked in details.