This book is intended to support a second course in computing, building upon knowledge which would have been acquired during an introductory course on programming. It would be the students first exposure to real computer science. This book introduces fundamental techniques of non-numerical computing, such as chaining, tables, and string-handling, when then lead on naturally to further courses on compiler construction, operating systems, data base management, artificial intelligence, and so on. The accent is on provided knowledge at all levels, from abstract to machine, with methods which are transferable across a wide body of problems.