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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Name: ____________________   Date: ____________

1.Easy
ABCF000?001?010?011?100?101?110?111?

The function F = ((A·B)·(A·C)′)′ is 0 for exactly one combination of the inputs. Click that row of the truth table.

F = ((A·B)·(A·C)′)′
  1. 1ABC = 000
  2. 2ABC = 001
  3. 3ABC = 010
  4. 4ABC = 011
  5. 5ABC = 100
  6. 6ABC = 101
  7. 7ABC = 110
  8. 8ABC = 111
2.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 AND function shown?

F = A·B
N =
3.Medium
ABCD000111100001111010010312041507061120130150141809111010

Use the Karnaugh map to find the minimal sum-of-products (SOP) form of F(A, B, C, D) = Σm(0, 2, 5, 8, 11, 12). How many product terms N does it have?

F(A, B, C, D) = Σm(0, 2, 5, 8, 11, 12)
N =
4.Medium
ABC000111100101324576

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

F = B′C′ + A′B′C + A′BC′ + BC
L =
5.Hard
CLKJK1234567

A positive-edge-triggered JK flip-flop starts with Q = 0 and receives the inputs shown. Click the first clock edge at which Q goes from 1 back to 0.

Q₀ = 0JK
  1. 1clock edge 1
  2. 2clock edge 2
  3. 3clock edge 3
  4. 4clock edge 4
  5. 5clock edge 5
  6. 6clock edge 6
  7. 7clock edge 7
6.Hard
DQ3​Q3​DQ2​Q2​DQ1​Q1​DQ0​Q0​CLKRING

A 4-bit ring counter Q₃Q₂Q₁Q₀ starts at 1000. 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 3 clock edges.

Q₃Q₂Q₁Q₀ = 10003
Q =

Answer key

  1. 1. ABC = 110
  2. 2. N = 2
  3. 3. N = 4
  4. 4. L = 5
  5. 5. clock edge 5
  6. 6. Q = 1

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