The picture below shows a PLA, I have done part (a) and found out that; $$ F_0 = A_0 \mathbin{\oplus} B_0 \\ F_1 = A_0B_0 + (\overline{A_0} + \overline{B_0})(A_1 \mathbin{\oplus} B_1) \\ F_2 = A_0B_0(A_1 + B_1) + A_1B_1\\ $$

What may this circuit be doing, I can't see a function for it?


I have got the output fro a program, i would want another opinion of what it may be doing, so that I can edit my guess;


-------------------------------------------------------------> EDIT

I don't get it, may be am not good at realizing patterns, I have interchanged both 1st and 3rd output and don't see a thing


  • \$\begingroup\$ Create a table of all 16 possible inputs and their output values and the answer will likely be obvious to you. \$\endgroup\$ – Edward Oct 22 '14 at 2:39
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    \$\begingroup\$ i got the output but still confused on what it could be doing \$\endgroup\$ – user124627 Oct 22 '14 at 3:28
  • \$\begingroup\$ Swap the order of your 1st and 3rd output columns (and maybe put a space between your A vs B input ones) and you might see it. \$\endgroup\$ – Chris Stratton Oct 22 '14 at 4:05
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    \$\begingroup\$ OH thanks guys, I realized it. This is adding A+B = F \$\endgroup\$ – user124627 Oct 22 '14 at 5:11
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    \$\begingroup\$ Congrats. Now that you have your answer, post it in the answer form so the question shows as resolved. \$\endgroup\$ – Chris Stratton Oct 22 '14 at 15:13

The circuit is an adder with \$F[2:0]=A[1:0]+B[1:0]\$.

  • \$\begingroup\$ Despite the comment of @ChrisStratton, the OP has not posted the answer in the comments as an actual answer. I've posted in as an actual answer so that the question does not remain unanswered. \$\endgroup\$ – Joel Reyes Noche Jan 14 '15 at 8:01

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