Computers are electronic devices; the most fundamental hardware elements of a computer control the flow of electricity. In a very primitive sense, we use technology to harness the power of a lightning bolt, bending it to our will so that we can perform calculations and make decisions. This chapter dances the fine line between computer science and electrical engineering, examining the most basic hardware elements in a computer.

In Chapter 2, we looked at number systems in general and at the binary number system in particular. As we saw in Chapter 3, the binary number system is of special interest because it is used to represent data in a computer. In this chapter, we explore how computers use electrical signals to represent and manipulate those binary values.