Code: The Hidden Language of Computer Hardware and Software

by Petzold Charles

Three dots, three dashes, and three dots represent SOS, the international distress signal. SOS isn’t an abbreviation for anything—it’s simply an easy-to-remember Morse code sequence.

What we’re doing by analyzing binary codes is a simple exercise in the branch of mathematics known as combinatorics or combinatorial analysis. Traditionally, combinatorial analysis is used most often in the fields of probability and statistics because it involves determining the number of ways that things, like coins and dice, can be combined. But it also helps us understand how codes can be put together and taken apart.

During storms, the bottoms of clouds accumulate electrons while the tops of clouds lose electrons; eventually, the imbalance is evened out with a stroke of lightning. Lightning is a lot of electrons moving very quickly from one spot to another.

In all batteries, chemical reactions take place, which means that some molecules break down into other molecules, or molecules combine to form new molecules. The chemicals in batteries are chosen so that the reactions between them generate spare electrons on the side of the battery marked with a minus sign (called the negative terminal, or anode) and demand extra electrons on the other side of the battery (the positive terminal, or cathode). In this

Some substances are significantly better than others for carrying electricity. The ability of an element to carry electricity is related to its subatomic structure. Electrons orbit the nucleus in various levels, called shells. An atom that has just one electron in its outer shell can readily give up that electron, which is what’s necessary to carry electricity. These substances are conducive to carrying electricity and thus are said to be conductors. The best conductors are copper, silver, and gold. It’s no coincidence that these three elements are found in the same column of the periodic table. Copper is the most common substance for making wires.

Just about anything will conduct electricity, however, if the voltage is high enough.

Consider a brick. Sitting on the floor, the brick has very little potential. Held in your hand four feet above the floor, the brick has more potential. All you need do to realize this potential is drop the brick. Held in your hand at the top of a tall building, the brick has much more potential. In all three cases, you’re holding the brick and it’s not doing anything, but the potential is different.