blog dds: 2021-06-18 — The Evolution of the Unix System Architecture
Unix has evolved for more than five decades, shaping modern operating systems, key software technologies, and development practices. Studying the evolution of this remarkable system from an architectural perspective can provide insights on how to manage the growth of large, complex, and long-lived software systems. In 2016 my colleague Paris Avgeriou and I embarked on this study aiming to combine his software architecture insights with my software analytics skills. Here is a brief summary of the study, which was published this month in the IEEE Transactions on Software Engineering.
Starting from the 1970 PDP-7 Unix version (2489 lines of kernel code and 9095 lines of programs; all written in assembly language), we studied main Unix releases leading to the FreeBSD lineage (currently more than 20 million lines of code) shown as orange boxes in the figure below.
Along those releases we examined core architectural design decisions, the number of features, and code complexity. We did that based on the analysis of the following:
