CompTIA A+ Certification All-in-One Exam Guide

Figure 3-5 Here “1” means on, “0” means off.
In computers, wires repeatedly turn on and off. As a result, we can use this
“1 and 0” or binary system to describe the state of these wires at any given
moment. (See, and you just thought computer geeks spoke in binary to
confuse normal people. Ha!) There’s much more to binary numbering in
computing, but this is a great place to start.
Registers
The Man in the Box provides good insight into the workspace inside a CPU.
The EDB gives you a way to communicate with the Man in the Box so you
can give him work to do. But to do this work, he needs a worktable; in fact,
he needs at least four worktables. Each of these four worktables has 16 light
bulbs. These light bulbs are not in pairs; they’re just 16 light bulbs lined up
straight across the table. Each light bulb is controlled by a single switch,
operated only by the Man in the Box. By creating on/off patterns like the
ones on the EDB, the Man in the Box can use these four sets of light bulbs to
work math problems. In a real computer, these worktables are called registers
(see Figure 3-6) and store internal commands and data.