I'm solving previous' years exams problems and i'm having trouble understanding one part of the problem. So I solve the first part and I have the truth table which is:

two muppets I did elimination with Karnaugh and I've got that output D is (A'B + C). Now, the second part says that I've got decoders of all combinations and OR chips. It wants me to implement the circuit with the simplest possible way.

Now, I know that with decoders I can implement all circuits and when I've got functions in format of sums (Σ1,2,3,5,7 in this case) I can use a decoder but I've got only one output function and all the exercises i've seen have 2+ outputs. What do i do? I create one 3x8 Decoder and a 5-input OR gate?


1 Answer 1


what if you make C one of the inputs to the or gate?

how about (A'B) in an encoder and a 2 input or gate to combine C

  • \$\begingroup\$ So what would be the final circuit? Is this considered the simplest implementation? \$\endgroup\$
    – Georgio3
    Jun 11, 2016 at 12:11
  • \$\begingroup\$ just a two input encoder with the A'B output going into a 2 input or gate combining that with C. I can't immagine anything having fewer parts or wires. \$\endgroup\$
    – Jasen
    Jun 11, 2016 at 12:17

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