$5-5.$ Explain why each of the following microoperations cannot be executed

during a single clock pulse in the system shown in Fig. $5-4.$ Specify a

sequence of microoperations that will perform the operation.

a$.$ IRlarrM$[PC]$

b$.$ AClarrAC$+TR$

c$.$ DRlarrDR$+AC,($AC does not change$)$