English: A 4-bit binary counter should add the step A for each clock cycle, where A can be 0, 1, 2 or 3. After 1111 comes 0000. A solution with a state table results in a 6-bit K-map and much work. a) Design the counter using 4 DFFs and a 4 bit full adder. b) Design another counter that adds 2 if x = 0 and subtracts 3 if x = 1. Present state Q4 Q3 Q2 Q1 0000 0001 0010 0 0 1 1 0100 0101 0110 0 1 1 1 1 0 0 0 1 0 0 1 1010 10 11 1100 1 1 0 1 1 1 10 1 1 1 1 Next state A=00 Q4 Q3 Q2 Q1 Next state A=01 Q4 Q3 Q2 Q1 Next state A=10 Q4 Q3 Q2 Q1 Next state A=11 Q4 Q3 Q2 Q1