What special purpose register does the DECODE stage use to determine the instruction opcode and operands? The PC The MAR The MDR The IR Reference Figure C.3, Page 570 in your book. Which hardware element, controlled by the LC- 3 State Machine, selects between using an immediate value or a second source register for ADD and ANDinstructions? CALU PCMUX OSRAMUX O REG FILE Referencing Figure C.3 again, what does the control signal ALUK that feeds the ALU decide? Which source operand to use in the calculations Whether the ALU is on or off Whether the ALU should perform an ADD, AND, or NOT If the ALU should write to memory Enter a single LC-3 instruction (in binary) that achieves the desired result. You must put spaces in the instruction to separate the bit fields. (a) Set the value of R4 to zero without affecting any other register