a$)$ The microprogrammed control organization has the following propagation delay times. $40$ ns to generate the next address, $10$ ns to transfer the address into the control address register, $40$ ns to acccss the control memory ROM, $10$ ns to trans fer the microinstruction into the control data register, and $40$ ns to perform the requircd microopcrations specificd by control word. What is the maximum clock frequcncy that the control can use? What would the clock frequency be if thc control data register is $5$ not used?