Electric components

All electrical circuits (including digital circuits) are made of these basic electric components:

Most commonly used components in digital circuits
 

Digital circuits are mainly made with these electronic components:

Resistors Transistors
 

But:   in this course we will not work with basic electronic components

We will be working with basic logical circuits that are built using basic electronic components

Elementary digital circuits
 

  • Elementary digital circuit can perform the basic logical operations

  • Elementary digital circuits are also called gates

  • The elementary digital circuits are:

      • The NOT gate
      • The AND gate (and the NAND gate)         
      • The OR gate (and the NOR gate)
      • The XOR gate

    Each gate has a unique diagram/symbol (discussed next)

  • Complex digital circuits (e.g., a CPU) are made of many elementary digital circuits

The NOT gate
 

Symbol and function of the NOT gate:

 

 

  • A NOT gate has 1 input signal
  • A NOT gate has 1 output signal
  • The output signal's value is equal to the inverse of the input signal's value

DEMO: cs355sim /home/cs355001/demo/circuits/not

FYEO: How to construct a NOT gate
 

The AND gate

Symbol and function of the AND gate:

  • A AND gate has k input signals
  • A AND gate has 1 output signal
  • The output signal's value is equal to the logical AND result of the input signal's value

DEMO: cs355sim /home/cs355001/demo/circuits/and3

FYEO: How to construct an (2 inputs) AND gate
 

The OR gate

Symbol and function of the OR gate:

  • An OR gate has k input signals
  • An OR gate has 1 output signal
  • The output signal's value is equal to the logical OR result of the input signal's value

DEMO: cs355sim /home/cs355001/demo/circuits/or3

FYEO: How to construct an (2 inputs) OR gate
 

The XOR gate

Symbol and function of the XOR gate:

  • A XOR gate has k input signals
  • A XOR gate has 1 output signal
  • The output signal's value is equal to 1 if an only if there are an odd # of 1 values in the input signals

DEMO: cs355sim /home/cs355001/demo/circuits/xor5

The NAND gate (= Not-AND gate)

Symbol and function of the NAND gate:

  • A NAND gate has k input signals
  • A NAND gate has 1 output signal
  • The output signal's value is equal to the inverse of the AND gate

DEMO: cs355sim /home/cs355001/demo/circuits/nand

The NOR gate (= Not-OR gate)

Symbol and function of the NOR gate:

  • A NOR gate has k input signals
  • A NOR gate has 1 output signal
  • The output signal's value is equal to the inverse of the OR gate

DEMO: cs355sim /home/cs355001/demo/circuits/nor