In Berkeley EECS is one department and classes are numbered as levels of abstraction (that was the original idea, it kinda works but somewhat derailed). 100 to

In Berkeley EECS is one department and classes are numbered as levels of abstraction (that was the original idea, it kinda works but somewhat derailed). 100 to roughly 140s are EE courses; 150 is CPU design, machine design, embedded systems etc; 160s is systems (security, operating systems, compilers, networking, software engineering); 170s is theory (algorithms, theory of computation, stochastic algorithms, computational biology); 180s is ... I guess misc high-level stuff (graphics, databases, artificial intelligence, natural language processing, machine learning). So from 100 to 189 goes from lowest level (semiconductor physics) to highest level. 190s are reserved for university-wide courses like research, experimental courses, deCal (classes offered by undergrad students) etc...