There's lots of hard CS content you can learn and take exams in without writing code. Logic design, complexity theory and automata, graph theory theorem proofs,

There's lots of hard CS content you can learn and take exams in without writing code. Logic design, complexity theory and automata, graph theory theorem proofs, linear algebra, complex analysis, coding theory (compression, encryption, ...), algorithms, proofs about data structures, operating system theory (scheduling algorithms, deadlocks, race conditions, virtual memory), database theory, etc.