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 = 1N1G1G2G3F

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

A = 1B = 0C = 1
  1. 1N1
  2. 2G1
  3. 3G2
  4. 4G3
2.Easy
ABCN1G1N2G2G3F

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
ABCD000111100001111000010302040517161120131150141819011110

Use the Karnaugh map to find the minimal product-of-sums (POS) form of F(A, B, C, D) = Σm(6, 7, 8, 9, 10, 12, 15). How many sum terms (factors) N does it have?

F(A, B, C, D) = Σm(6, 7, 8, 9, 10, 12, 15)
N =
4.Medium
MUXCI0​C′I1​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 = C′I₂ = 1I₃ = 1
N =
5.Hard
TQ0​Q0​TQ1​Q1​TQ2​Q2​CLKMOD-5

A synchronous mod-5 counter counts 0, 1, …, 4 and then returns to 0. It starts at 3. Which count Q (in decimal) does it show after 9 clock pulses?

Q0 = 39N = 5
Q =
6.Hard
ABCD0001111000011110X0111302X41507X6112013115X140809011010

For F(A, B, C, D) = Σm(1, 3, 5, 12, 15) + d(0, 4, 6, 14), where d marks the don't-care conditions, find the number N of essential prime implicants.

F(A, B, C, D) = Σm(1, 3, 5, 12, 15) + d(0, 4, 6, 14)
N =

Answer key

  1. 1. G3
  2. 2. N = 5
  3. 3. N = 5
  4. 4. N = 6
  5. 5. Q = 2
  6. 6. N = 4

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