Skip to main content
Logo image

Digital Electronics: Supplement to Engs 31 / CoSc 56

Eric W. Hansen

Chapter 2 Electronic Logic

In Section 1.5 we made the following points about the electrical representation of logic:
  • Logical TRUE (1) and FALSE (0) are electrically represented by HIGH and LOW voltage levels; commonly, LOW is about 0.5V and HIGH is about 3V.
  • The usual pairing is HIGH with TRUE and LOW with FALSE, although there are occasions when the pairings are reversed.
  • The logical AND, OR, and NOT operations are realized by electronic circuits called logic gates, each with a distinct symbol, as illustrated below
described in detail following the image
Figure 2.0.1. AND, OR, and NOT symbols on a logic diagram for the \(x \lt 2\) function.
In this chapter we will expand each of these points, addressing the following questions:
  • How are AND, OR, and NOT gates constructed?
  • What are the actual characteristics of logic gates?
  • Why would anyone deviate from the pairing of HIGH with TRUE and LOW with FALSE?
PrevTopNext