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
A = 1B = 0C = 0N1G1G2F

The inputs of the logic circuit are A = 1, B = 0 and C = 0. Exactly one of its gates has the output 0. Click that gate.

A = 1B = 0C = 0
  1. 1N1
  2. 2G1
  3. 3G2
2.Easy
A = 0B = 0C = 1G1G2G3F

The inputs of the logic circuit are A = 0, B = 0 and C = 1. Exactly one of its gates has the output 0. Click that gate.

A = 0B = 0C = 1
  1. 1G1
  2. 2G2
  3. 3G3
3.Medium
ABC000111100101324576

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

F = AB + AB′ + AC
L =
4.Medium
ABCD000111100001111000011302140517160120131150141809111010

Use the Karnaugh map to find the minimal sum-of-products (SOP) form of F(A, B, C, D) = Σm(3, 4, 6, 7, 8, 11, 15). How many literals L does it contain in total (a primed variable counts as one literal)?

F(A, B, C, D) = Σm(3, 4, 6, 7, 8, 11, 15)
L =
5.Hard
DQ3​Q3​DQ2​Q2​DQ1​Q1​DQ0​Q0​CLKSHIFT

A 4-bit shift register Q₃Q₂Q₁Q₀ holds 0111. At every clock edge the bits shift one place to the right (Q₃ → Q₂ → Q₁ → Q₀, Q₀ is lost) and the serial input enters Q₃. The serial input is 1, 1, 1, 0, 1 at the 5 edges. Give the final state Q = Q₃Q₂Q₁Q₀ as a decimal number.

Q₃Q₂Q₁Q₀ = 01111, 1, 1, 0, 1
Q =
6.Hard
DQ3​Q3​DQ2​Q2​DQ1​Q1​DQ0​Q0​CLKRING

A 4-bit ring counter Q₃Q₂Q₁Q₀ starts at 1100. At every clock edge the bits shift one place to the right (Q₃ → Q₂ → Q₁ → Q₀) and Q₃ receives Q₀. Give the state Q = Q₃Q₂Q₁Q₀ as a decimal number after 5 clock edges.

Q₃Q₂Q₁Q₀ = 11005
Q =

Answer key

  1. 1. G1
  2. 2. G1
  3. 3. L = 1
  4. 4. L = 9
  5. 5. Q = 11
  6. 6. Q = 6

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