This course is the first part of the two-semester introduction to Computing Science. It explains the design principles of a computer from the execution of a simple program on an instruction set architecture to the basic techniques for the specification, design and optimisation of the individual components of a computer to the basic components such as gates, flip-flops and registers. Typical examples of combinational circuits, such as adders, are used to illustrate modular design techniques. More advanced design techniques are discussed for sequential circuits, i.e. circuits with memory behaviour, and illustrated using example circuits.