This introductory chapter presents the testing needs of digital circuits, the difficulties of testing, which increase with the complexity of VLSI (very large scale integrated) circuitry, and the main ways to tackle them (Section 1.1). Builtin self-test (BIST) is an approach allowing some of the most important problems to be solved. The main features of BIST are presented in Section 1.2. Pseudorandom generators are widely used as build-in test pattern generators. Some fundamental questions arise about random testing (which can also be used without BIST); they are stated in Section 1.3, then tackled in the rest of the book.

In this first chapter, some terms might be unknown to a reader who has no knowledge of the test field. The more specific terms are explained. The very basic notations and concepts will be introduced in Chapter 2 and subsequent chapters.