Though this book has a lot of good content in it, it has many mistakes. Many of the programs are wrong and so is the theory, it has contradictory points, like in one question it says ROM is volatile but in the next it says ROM is non volatile. This is just one of them, it has many more things which are incorrect, many of the programs it shows don't even work properly. I request that you should double check the content before publishing it as it may affect others a lot who depend on such books.