Write the full name of the following important registers in CPU and describe their role briefly. (a) MAR (b) MBR (c) PC (d) IR 11. Define the four action categories of a processor. 12. Draw the Instruction Execution Cycle and label the states with names. 13. Define what is an Interrupt. Name any two categories of interrupt. 14. State one difference between Bus and Point to Point interconnection structures.