15. For the parallel-adder, determine the complete sum by analysis of the logical operation of the circuit. Verify your result by longhand addition of the two input numbers. 16. For the 4-bit comparator, plot each output waveform for the inputs shown. The outputs are active-HIGH. 17. Show the decoding logic for each of the following codes if an active-HIGH (1) output is required: (a) 1101 (b) 1000 (c) 11011 (d) 11100 (e) 101010 (f) 111110 (g) 000101 (h) 1110110 18. For the decimal-to-BCD encoder logic, assume that the 9 input and the 3 input are both HIGH. What is the output code? Is it a valid BCD code