8.
After identifying the overall type of circuit, determining where the expression must first be
separated, and drawing the logic symbol which represents the overall circuit, the next step is
to convert all groups or letters within the expression systematically until only single-letter
inputs remain. For example, the Boolean expression AB (C+D) is converted to a logic
diagram as follows:
Step 1. Identify the overall type of circuit.
a. A B (C+D) - this signifies an AND gate.
b. The AND gate contains three inputs-A, B, and quantity (C+D).
c. The logic AND symbol with three inputs is shown below.
NOTE: Input C+D is now without parentheses, since it has been separated
from the other group and no longer needs a sign of grouping.
Step 2. Identity the input C+D.
a. C + D- this signifies an OR gate.
b. The OR gate contains two inputs-C and D.
c. Draw the logic OR symbol with two inputs as shown below.
IT 0343
2-10
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