Digital logic: gates, K-maps & flip-flops worksheet with answers

Free printable Digital logic: gates, K-maps & flip-flops worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
BAF

NAND and NOR are universal gates: any logic function can be built from one of them alone. What is the minimum number N of 2-input NAND gates needed to build the NOR function shown?

F = (A + B)′
N =
2.Easy
ABCG1G2F

For the logic circuit shown, how many of the 8 combinations of the inputs A, B and C give the output F = 1? Find N.

A, B, C → F
N =
3.Medium
MUXCI0​CI1​1I2​1I3​ABS1​S0​F

A 4-to-1 multiplexer has its select inputs S₁ = A and S₀ = B, and its data inputs tied to I₀ = C, I₁ = C, I₂ = 1, I₃ = 1. For how many of the 8 combinations of A, B and C is the output F = 1? Find N.

I₀ = CI₁ = CI₂ = 1I₃ = 1
N =
4.Medium
ABC000111100101324576

Simplify F = ABC + A′C + AB′C to its minimal sum-of-products form. How many literals L does the simplified expression contain?

F = ABC + A′C + AB′C
L =
5.Hard
ABCD0001111000011110001113X21405X7X6012013015X140819011010

Find the minimal SOP form of F(A, B, C, D) = Σm(1, 3, 4, 9) + d(2, 6, 7, 14), where d marks the don't-care conditions. How many product terms N does it have?

F(A, B, C, D) = Σm(1, 3, 4, 9) + d(2, 6, 7, 14)
N =
6.Hard
DQ3​Q3​DQ2​Q2​DQ1​Q1​DQ0​Q0​CLKJOHNSON

A 4-bit Johnson counter Q₃Q₂Q₁Q₀ starts at 0000. At every clock edge the bits shift one place to the right (Q₃ → Q₂ → Q₁ → Q₀) and Q₃ receives the inverse of Q₀. Give the state Q = Q₃Q₂Q₁Q₀ as a decimal number after 11 clock edges.

Q₃Q₂Q₁Q₀ = 000011
Q =

Answer key

  1. 1. N = 4
  2. 2. N = 5
  3. 3. N = 6
  4. 4. L = 1
  5. 5. N = 3
  6. 6. Q = 14

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