The ARM processor is executing the main program. However, the processor is forced to execute an interrupt service routine $($ISR$)$ originating from operating system subroutine call. Furthermore, a second ISR is triggered and forces the processor to call a programmed subroutine that performs arithmetic operations

aName and explain the type of exception that triggered the first ISR and the address of the exception in the vector table

bName and explain the operating mode of the processor when the first ISR is triggered

cName and explain the instructions to be executed to enable the processor to move to the mode in b