The Big Book Has Arrived

All in One A+ Certification Exam Guide Fifth Edition by Michael Meyers & Scott Jernigan.

The Big A+ book landed on my desk yesterday. This thing looks like a dictionary. At first glance it is clear that this book is much more exhaustive than the Dummies book. I read through the chapter on Microprocessors and it seems to be pretty up to date, It mentions SATA drives and L3 Cache, topics that, due to age, were omitted from the other book I'm using.

Nevertheless I am glad I have the Dummies book. It is more of a gloss. Then when I really want to drill down and Geek Out this Monster Book is going to be just the ticket.

Chapter 3 Microprocessors - has a great little anology about how the Microprocessor works called, "The Man in the Box". The gist of it is that the CPU can be compared to this little guy inside a box in the computer. He is a real whiz and can do just about any mathematical computation we out in front of him. Now the challenge is to find a way to communicate with him, and beyond that to make him do what we want and then return the result in a fashion that we can understand.

The solution for getting Data in and out to the Man in the Box is the External Data Bus or EDB. Back to the Analogy: Meyers says that we should imagine that we have a set of 8 light switches that control 8 light bulbs inside the box where the little man can see them. In addition the man also has a set of 8 switches and we have our own set of lightbulbs. So we have a set of 16 switches and bulbs and we communicate to one another through various combinations of lights. Each of us has a "code book" se we know what means what.

What are the codes? Well once again he asks us to imagine that the man in the box has 4 different work tables. Each table represents the CPUs general purpose resiters where the machine actually does the calculation. Obviously there are a lot more than 4 but for the sake of this narrative the author foceus on 4 the AX, BX, CX, and DX general purpose registers. Instead of having only 8 lights to work with these tables in our example have 16.

The author is very careful to note that this is all just anaolgy and that instead of lights what we are really dealing with is a bunch of semicondictive wires that alternate between on and off and can thusly mimick the same kind of code stuff as our Man in the Box. All of this code stuff is called "Machine Language"

I will create a post in the near future about how the "clock" works in the microprocesor and how this clock controls the speed at which the man in the box can crucnch his numbers. At that Time I will talk a little about the terminology of "Clock Speed"