Overview

The great success story of digital electronics is due to one simple fact: information can be reduced to a stream of binary data which can be represented as one of two discrete voltage levels. This data can be manipulated and processed at will, and the quantity of information you can process depends only on the speed at which you can do it. The infinite variability of analogue voltage levels is replaced by two dimensions of quantization, in voltage and time. In theory, all voltage levels below a given threshold represent binary 0, and all levels above the threshold represent binary 1. Again in theory, time is divided into discrete units by a reference clock, and the boundary between each unit marks the transition from one bit of data to the next.

By this means, the unpredictability and variability of analogue, or linear, electronic phenomena is factored out of the design process. (It is replaced by another kind of unpredictability and variability, that of complex software phenomena, but that is not the subject of this book.) Voltage drift, component tolerances, offsets and impedance inaccuracies become instantly irrelevant. At the same time, programmability allows a single piece of hardware to perform widely different tasks, including ones that perhaps were not even envisaged when it was designed and built. To incorporate such programming flexibility into analogue hardware would be impossible.

The millions of successful digital designs worldwide testify to these advantages. At the same time, much to the relief of those who...