3. Indicate the dots required to be connected (1 to 8) to implement a NOR function using the PLD AND array shown below:

  1. Dots at 3, 8
  2. Dots at 2, 4, 7, 8
  3. Dots at 2, 4 (only)
  4. Dots at 5, 7, 1, 2
  5. Dots at 5, 7 (only)

4 is CORRECT. Placing dots at 5 and 7 forms the product I1'I2' for the bottom AND gate. Also, dots at 1 and 2 forms the product I1'I1 = 0 for the top AND gate. The Oring of these 2 AND gate then yields: 

I1'I2' + I1I1' = I1'I2' = (I1 + I2)'  [DeMorgan's law]
which is the NOR function. Note further that placing dots at the following connection points would also generate a NOR: 5,7,3,4; 1,3,5,6; 1,3,7,8.

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