1. How many invalid (unused) code sequences can we have in 5B/6B encoding? How many in 3B/4B encoding?
2. What is the result of scrambling the sequence 11100000000000 using each of the following scrambling techniques? Assume that the last non-zero signal level has been positive.
a. B8ZS
b. HDB3 (The number of nonzero pulses is odd after the last substitution.)