Give the sequence of steps needed to fetch and execute the two special instructions

MoveControl Ri, IPS

and

MoveControl IPS, Ri

used in Example 5.6

Problem: Example 5.5 illustrates how the contents of the PC and the PS are saved when Example 5.6 an interrupt request is accepted. In order to support interrupt nesting, it is necessary for the interrupt-service routine to save these registers on the processor stack, as described in Section 3.2. To do so, the contents of the PS, which are saved in register IPS at the time the interrupt is accepted, need to be moved to one of the general-purpose registers, from where they can be saved on the stack. Assume that two special instructions Move Control Ri, IPS and Move Control IPS, Ri are available to save and restore the contents of IPS, respectively. Suggest changes to the hardware in Figures 5.8 and 5.10 to implement these instructions. Solution: A possible organization is shown in Figure 5.28. To save the contents of IPS, its output is connected to an additional input on MuxY. When restoring its contents, MuxIPS selects register RA