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.

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
ABCN1: 1 nsN2: 1 nsG12 nsN3: 1 nsG23 nsG38 nsF

The propagation delay of every gate is written under it. Find the worst-case propagation delay tpd from the inputs to the output F.

N1: 1 nsN2: 1 nsN3: 1 nsG1: 2 nsG2: 3 nsG3: 8 ns
tpd = ns
2.Easy
ABCG1G2G3F

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
MUXC′I0​0I1​CI2​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 = 0, I₂ = C, I₃ = 1. For how many of the 8 combinations of A, B and C is the output F = 1? Find N.

I₀ = C′I₁ = 0I₂ = CI₃ = 1
N =
4.Medium
ABCD000111100001111000111302041507161120130150141809011110

Use the Karnaugh map to find the minimal sum-of-products (SOP) form of F(A, B, C, D) = Σm(1, 3, 5, 6, 8, 10, 12). How many literals L does it contain in total (a primed variable counts as one literal)?

F(A, B, C, D) = Σm(1, 3, 5, 6, 8, 10, 12)
L =
5.Hard
ABCD00011110000111100001030214150706X120130151141819X11X10

Find the minimal SOP form of F(A, B, C, D) = Σm(4, 5, 8, 9, 14) + d(10, 11, 12), where d marks the don't-care conditions. How many literals L does it contain?

F(A, B, C, D) = Σm(4, 5, 8, 9, 14) + d(10, 11, 12)
L =
6.Hard
TQ0​Q0​TQ1​Q1​TQ2​Q2​TQ3​Q3​CLKMOD-10

A synchronous decade (mod-10) counter counts 0, 1, …, 9 and then returns to 0. It starts at 7. Which count Q (in decimal) does it show after 19 clock pulses?

Q0 = 719N = 10
Q =

Answer key

  1. 1. tpd = 12 ns
  2. 2. N = 4
  3. 3. N = 4
  4. 4. L = 16
  5. 5. L = 7
  6. 6. Q = 6

Full step-by-step solutions: practise this topic on examproblems.com.