Question

What must the address field of an indexed addressing mode instruction be to make it the same as  a register indirect mode instruction?? how?

Answer 1

Index Addressing Mode, Effective Address EA₁=Base Adress +[Index Register] i.e Base Adress+content of Index Register

                                                               DATA=[EA₁] i.e. content of EA₁

Indirect Addressing Mode, Effective Address EA₂=[Register]i.e. content of Register

                                                               DATA=[EA₂] i.e. Content of EA₂

=================> Address Field |0(register name)| will make Base Address=0, and EA₁ and EA₂ will become equal