An instruction set for a specific architecture is called the ISA. Each processor

Question

   An instruction set for a specific architecture is called the ISA. Each processor has its own ISA. You know that the lw instruction will get a constant value and a register, and the summation of these two numbers will be used as the address of the memory location. Now assume you are asked to add a new instruction to this processor with the following specifications:
    Instruction: LWI Rt, Rd(Rs)
    Interpretation: REG[] = MEM[Reg[Rd] + Reg[Rs]]
    Difference between this instruction and regular LW is that the address
    is based on the data of two registers instead of the constant value and
    one register.
    (a) Which existing block will you need for LWI?
    (b) Which new function or block you need to add (if any) for this instruction to the single cycle processor.
    (c) What changes need to be made in control unit for this instruction (if any)? Explain your answer.

Explanation / Answer

a) For LWI, we need Instruction memory, existing read and write ports of registers and the ALU

b) In Single cycle processor , we need to add additional read port in registers and either a second ALU or a third input to existing ALU

c) We need to change the ALU operation control signals to support the added ALL operation in the ALU,

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.