The third edition of this student text reflects the developments that have taken place in the digital field in recent years. It has new chapters, for example, on combinational logic design using MSI and programmable logic devices. The text is suitable for those students on digital logic courses in Electronics and Computer Departments at college, polytechnic and university level. It includes a greater range of examples and problems for such students. The book reflects developments that have taken place in the digital fields in recent years. There have been changes in the way logic devices are represented symbolically so new functional logic symbols have been introduced. A new chapter on number systems and codes, the ASM method of designing sequential circuits has been added. Also a further look at single-bit memory elements which emphasizes the difference between latches and flip-flops have is included.