IT212 Lecture 3: Logic Gates and Boolean Algebra

What are the single input logic gates?

• NOT

• BUF

  • Just keeps the variable as is

What are the two-input logic gates?

• AND

• OR

• XOR

  • Outputs a 1 only one exactly one of its inputs are true

• NAND

• NOR

• XNOR

  • Outputs a 1 only when both of its inputs are the same

What are the multiple input logic gates?

• NOR3

  • Takes 3 values and only outputs a 1 if all values are equal to 0

What do discrete voltages represent?

1 and 0

• 0 = ground or 0 volts

• 1 = V or 5 volts

Is 4.99 volts a 0 or a 1?

It is a 1 because it is closer to 5 than 0.

What is noise?

Anything that degrades the signal.

• Resistance, power supply noise, coupling to neighboring wires, etc.

What is the static disipline?

• With logically valid inputs, every circuit element must produce logically valid outputs.

• Use limited ranges of voltages to represent discrete values

When are two logic circuits equivalent?

If for all combinations of the inputs, their outputs are the same.