Description:System software is generally considered as a tough subject by students, But the way in which this book has been organized will remove this perception. It begins with the introduction and role of various softwares needed to execute a program i.e. which system software is required to perform each step through which a program undergoes in order to get executed by the computer system. Then the internal workings of each of these softwares is provided in subsequent chapters. In order to explain the concepts, flowcharts, tables, diagrams and assembly language program examples are given. This book can also help general readers to understand how a computer program actually works.