As pictured in Figure 2-1, the analog signal fluctuates among a series of values, all of
which are represented on the wave line. This could represent the rise and fall of a sound
wave or any other event made up of a series of related increasing or decreasing values.Computing in Binary Numbers
The primary storage device inside the computer is the transistor. Yes, the same device
that made radios small enough to fit in your shirt pocket in the 1960s is the same miracle
of science that allows your computer to store and process millions of bits of data. A single
transistor is capable of holding an electrical charge that is either positive or nonpositive.
Since the objective of the computer is to manipulate data, the electrical states of the tran-
sistor (positive and nonpositive) are assigned the numerical values of 1 and 0 (zero). It
may seem that you can’t do very high math, or even low math for that matter, with only a 1
and a 0, but using the binary number system, the computer is fully capable of performing
all of its magic. Figure 2-2 shows the two values of binary in contrast to the two states of
the transistor.The Binary Number System
The binary (the prefixbimeaning two) number system uses only the two values: 0 and 1.
This matches the capabilities of the transistor perfectly, as the transistor can also have
only two states or values. As shown in Figure 2-2, the two values of the binary number
system and the two states of the transistor can be paired up so that the transistors positive
state represents the value 1 and its nonpositive state represents the value 0. The bonding
of these two systems allows the computer to use the binary number system.
The computer stores a single binary numeral (either a one or a zero) in asingletransis-
tor. In fact, the wordbitin computer lingo is a short form ofbinary digit. Each transistor
holds a single electrical charge that is either positive or nonpositive, which in turn repre-
sents a 1 or a 0. As we will discuss in Chapter 7, eight bits are grouped together to formChapter 2: Basic PC Concepts and Terminology^27
Figure 2-1. A comparison of a digital signal and an analog signal