But, it has been done in simpler forms on a few machines. Wait until the currently executing instruction finishes, then handle. It handles interrupts inbetween 2 instructions. If an interrupt is pending, handle it. PC update 4.
All instructions are available.
If interrupts are disabled, then the hardware is not checking to see if there are further interrupts to handle. Disabling makes sure that the handling of an interrupt is not interrupted. 4. saves current PC coprocessor C0, register 14, called Exception Program counter. Gives return address within user program. Where to return to when done handling the exception.