The serial adder uses two four$-$bit registers. Register A holds the binary number $0101$ and register $B$ holds $0111.$

The carry flip$-$flop is initially reset to $0.$ List the binary values in register A and the carry flip$-$flop after each shift.

Briefly explain counters. Design a counter with the following repeated binary sequence: $0,1,2,3,4,5,6$ using JK

flip$-$flops.

Write and verify the HDL behavioral and structural descriptions of the four$-$bit register.