$($a$)$ Explain the main different between a Static Random $-$ AccessMemories and Dynamic Random $-$Access Memories.$($b$)$ Determine the sequence of the counter shown in Figure $7$ and explain the function of NAND gate in the circuit. Begin with the condition that the counter is cleared. Show the appropriate waveforms for all input and outputs to support your answer$($c$)$ Design a synchronous counter that can count up and down for a sequence of $7$~$2$~$3$~$1$ using JK flip $-$ flops.$)$