hrases you should review and understand as you read through the rest of the book and more importantly, develop your own PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS set of knowledge and way of dealing with others where the subject matter is content transport in communications network environments. First, a little philosophy, and background perspective: Analog or Digital-Where did we come from, what are our individual backgrounds, and where are we headed? If you're a technician or engineer it's likely your background includes some level of formal education in basic electronics. After school you begin practicing your new knowledge by installing or repairing equipment. Depending on your age, you learned about tubes, tran- sistors, integrated circuits, large scale integrated circuits (LSIs), glue logic, central processing units (CPU), random access memory (RAM), read-only memory (ROM), and power supplies. Along the way, you came to appreciate not only the components themselves as individual pieces, capable of performing specific functions and by definition, incapable of performing lots of other functions better left to another component created to perform those functions or some limited set of all the functions in a larger system. You may have started the learning process when the electronic world was mostly analog, or if you're just out of school and beginning to practice you're at the opposite extreme because the electronics world is mostly digital, or at least it seems that way. There's another variation on this picture that may be helpful in understanding where we are and how we got to this point. It has to do with control systems. Somewhere along the way, electrical power found its way into not only powering mechanical systems, but con- trolling them as well. Control systems evolved along the same path as harnessed electricity did. Batteries produce only one polarity-direct current (DC)-and can be connected SO the positive or negative terminals use a common conductor, or buss to provide powe