Solution

Concept:

To determine the number of gate inputs required to realize an expression, you need to look at the number of terms and the number of literals (variables) in each term.

In the expression you've given: ABC + AB̅CD + EF̅ + AD

There are four terms and a total of nine literals:

• ABC has three literals.
• AB̅CD has four literals.
• EF̅ has two literals.
• AD has two literals.

Each literal requires input, and each term requires a separate AND gate (because the product implies AND operations), the inputs of which are the literals. The results of these AND gates then need to be ORed together, which requires one additional OR gate with four inputs.

So, in total, the number of gate inputs required would be:

1. AND gate inputs: 3 (for ABC) + 4 (for AB̅CD) + 2 (for EF̅) + 2 (for AD) = 11
2. OR gate inputs: 4 (because there are four terms)

So, the total number of gate inputs required is 11 (AND) + 4 (OR) = 15.

Note that the inputs A̅, B̅, etc., are usually achieved by passing the original inputs (A, B, etc.) through NOT gates. If you are considering these NOT gates also, then there will be an additional number of 2 inputs (for B̅, F̅) added to the total count making it 17.