The first five editions of this book were based on the idea that a computer can be regarded as a hierarchy of levels, each one performing some well-defined function. This fundamental concept is as valid today as it was when the first edition came out, so it has been retained as the basis for the sixth edition. As in the first five editions, the digital logic level, the microarchitecture level, the instruction set architecture level, the operating-system machine level, and the assembly language level are all discussed in detail
