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I don't understand the negative reviews. This is a very nicely written textbook (from a second year undergrad with only some familiarity with logic design). Explains everything crystal clear and shows motivation for everything. This is a good textbook to learn from as it is very pleasant to read and will improve your understanding of computer organization/assembly.
Although the textbook is nicely organized and full of great information, it is also full of typos. It is making my professor look very bad. He assigns our homework from this textbook, but there are a ridiculous amount of typos in the questions (and answers). It makes him look unprepared for lecture because he makes the mistake of trusting this book. Avoid this book until they add a few more revisions to fix the typos.