logic circuits


Succeeds: propositions

Summary

Logic gates

OperationGateOutput
NOTnot_gate.png
ANDand_gate.png
ORor_gate.png
NANDnand_gate.png
NORnor_gate.png
XORxor_gate.png
XNORxnor_gate.png

hollow circle represents a negation, solid circle represents a wire intersection

Universal gates

OperationNANDNOR
NOTnot_nand.pngnot_nor.png
ANDand_nand.pngand_nor.png
ORor_nand.pngor_nor.png

Half adder

  • arithmetic addition of 2 single bits
  • 2-bit output
0000
0101
1001
1110

half_adder.png

Concept

Logic circuits

  • circuit made up of logic gates
  • fan in -> number of inputs to a gate
  • every input must be connected for the circuit to work

Universal gates

  • any boolean function can be built using only NOT, AND and OR
  • {NOT, AND, OR} is a complete set of logic

NAND circuits

  • NAND can implement NOT, AND and OR
  • {NAND} is a complete set of logic
  • for SOP expressions

NOR circuits

  • NOR can implement NOT, AND and OR
  • {NOR} is a complete set of logic
  • for POS expressions

Application

SOP to NAND circuit

sop_nand.png

POS to NOR circuit

pos_nor.png