Digital electronics is at the very heart of the telecommunications revolution that has given us the digital computer, the Internet and, more recently, digital radio and television. Digital electronics is highly versatile and appears to be all-pervasive, yet there are still some electronic applications that are best dealt with using analogue techniques. As scientists, it is important to recognise that it is analogue electronics that often provides the interface between a measuring device and the physical world. When we digitise an analogue signal we trade in our continuous physical signal for one in which only certain values are allowed. This sacrifices some information, but comes with some major advantages, such as errorless data transmission. Uses of digital electronics ranges from small-scale tasks possible with just a few logic gates up to the complexity of large computer farms. This module starts with an introduction to binary arithmetic, logic gates and the laws of Boolean algebra. Techniques for designing and improving logic are then introduced and illustrated with examples. Various types of logic families will be discussed together with how to make logic gates from semiconductors. Finally, the various types of devices and flip-flops and their applications are explored in the context of the modern PIC microcontroller. The analogue part of the course focuses on the frequency domain analysis of some common operational amplifier circuits. We shall investigate the advantages and potential problems of negative feedback. We will also look at the problem of noise and signal recovery and the problems associated with the process of analogue-to-digital conversion.