Chapter 8.7, Problem 4QE

In the chapter, we introduced a machine instruction of the form O×DROS. Suppose we extended this form to OxDRXS, meaning “Load register R with the data pointed to by the value in registers plus the value X.” Thus the pointer to the data is obtained by retrieving the value in register S and then incrementing that value by X The value in register S is not altered (If register F contained 0x04, then the instruction 0xDE2F would load register E with the contents of the memory cell at address 0x06. The value of register F would remain 0x04.) What advantages would this instruction have? What about an instruction of the form OxDRTS—meaning “Load register R with the data pointed to by the value in register S incremented by the value in register T”?