The diagrams used here are similar in style and content to the environment diagrams used in SICP (Structure and Interpretation of Computer Programs), which is a

The diagrams used here are similar in style and content to the environment diagrams used in SICP (Structure and Interpretation of Computer Programs), which is an introductory (and quite comprehensive) CS text. At Berkeley at least -- and I think MIT as well -- SICP is taught in a course taken by both majors and non-majors are taking CS courses.