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DLDSemester 2ECE

Digital Logic Design Notes

Boolean algebra, combinational & sequential circuits, FSMs.

14 min read3 sectionsExam-ready notes

Key points

  • Boolean laws & K-maps
  • Adders, mux, decoder
  • Flip-flops (SR, JK, D, T)
  • Counters & registers
  • Mealy vs Moore FSM

1. Boolean Algebra

Laws: Identity, Null, Idempotent, Complement, Commutative, Associative, Distributive, De Morgan

De Morgan

  • (A·B)' = A' + B'
  • (A+B)' = A' · B'

K-Map: group 1s in powers of 2 for SOP minimization

2. Combinational Circuits

Output depends only on current inputs.

  • Half/Full Adder, Subtractor
  • Multiplexer / Demultiplexer
  • Encoder / Decoder
  • Comparator

No memory elements.

3. Sequential Circuits

Output depends on inputs + past state (memory).

Flip-flops: SR, JK, D, T

Registers: store multi-bit data

Counters: async (ripple), sync; up/down/mod-n

FSM

  • Moore — output depends on state only
  • Mealy — output depends on state + input