PHYS345 Electricity and Electronics

Hint for P9.21

Determine how one row of D's leads to the next row of Q's in the truth table - remember that this is sequential logic. You may study Table 9.1 in the textbook which is a truth table for a different counter.

Note also that there are four inputs: the enable bit E and the three data bits, D1, D2, and D3. There are three outputs: Q1, Q2, and Q3, not four as claimed in the last sentence of the problem statement. The objective is to derive the D's for the subsequent state from the Q's for the current state.

Construct Karnaugh mapping of EQ3\Q2Q1 to find the combination of gates needed to derive the D's from the Q's, similar to the process on pg. 253 of the textbook.

Last updated Nov. 6, 1998.
Copyright George Watson, Univ. of Delaware, 1998.