What He Will Try to Do
Our intent is to introduce you over the next chapters to come, to the world of computing. As we do so,
we have one objective above all others: to show you very clearly that there is no
magic to computing.
The computer is a deterministic system-every time we hit
it over the head in the same way and in the same place (provided, of course, it was
in the same starting condition), we get the same response. The computer is not
an electronic genius; on the contrary, if anything, it is an electronic idiot, doing
exactly what we tell it to do. It has no mind of its own.
What appears to be a very complex organism is really just a huge, systematically interconnected collection of very simple parts. Our job throughout this course is to introduce you to those very simple parts, and, step-by-step, build the
interconnected structure that you know by the name computer. Like a house, we will start at the bottom, construct the foundation first, and then go on to add layers and layers, as we get closer and closer to what most people know as a full-blown computer. Each time we add a layer, we will explain what we are doing, tying the
new ideas to the underlying fabric.
How We Will Get There
We will start by noting that the computer is a piece of electronic
equipment and, as such, consists of electronic parts interconnected by wires.
Every wire in the computer, at every moment in time, is either at a high voltage or
a low voltage. We do not differentiate exactly how high. For example, we do not
distinguish voltages of 115 volts from voltages of 118 volts. We only care whether
there is or is not a large voltage relative to 0 volts. That absence or presence of a
large voltage relative to 0 volts is represented as 0 or 1.
We will encode all information as sequences of 0s and 1s. For example, one
encoding of the letter a that is commonly used is the sequence 01100001. One
encoding of the decimal number 35 is the sequence 00100011. We will see how
to perform operations on such encoded information.
Once we are comfortable with information represented as codes made up
of 0s and Is and operations (addition, for example) being performed on these
representations, we will begin the process of showing how a computer works.
we will see how the transistors that make up today's microprocessors work. We will further see how those transistors are combined into larger structures that perform operations, such as addition, and into structures that allow
us to save information for later use. we will combine these larger
structures into the Von Neumann machine, a basic model that describes how a