I'll keep this in bullet form to be brief: • Implement a stack in your favorite language (I used C++) • How are arguments passed in C? (Where? What order?) • How does virtual memory work? Went into some detail on what happens on Linux when a page fault occurs. • How would you get the address of a field in a C struct? • Write a method to find the in order successor in a binary tree. • Debug this method in GDB. • What is the Big O complexity of this code? • Other computer science questions I can't recall. Essentially, you should know stacks, trees, heaps and other data structures, as well as basic sorting, searching and optimization algorithms.