$2.$ A computer responds to an interrupt request signal by pushing onto the stack the contents of PC and the current PSW $($program status word$).$ It then reads a new PSW from memory from a location given by an interrupt address symbolized by lAD. The first address of the service program is taken from memory at location lAD $+1.$ a$.$ List the sequence of microoperations for the interrupt cycle b$.$ List the sequence of microoperations for the return from interrupt instruction