Although real-time systems are becoming increasingly important they are often so embedded that we fail to notice them even while interacting with them. An important characteristic of real-time systems is that their correctness is time- dependent. Examples of such systems range from safety-critical ones, such as nuclear reactors and automotive controllers, to entertainment software such as games and graphics animations. The growing importance of real-time systems has made it a core area for computer science, electronics and communication, as well as electrical engineering students. This book is designed to serve as a textbook for both graduate and post-graduate level courses on real-time systems. It can also serve as a reference for practising engineers.