Here is Figure 4.24 1. (20 points) The basic single-cycle MIPS implementation in

Question

Here is Figure 4.24

1. (20 points) The basic single-cycle MIPS implementation in Figure 4.24 can only implement a subset of instructions. If we want to implement the "add immediate (addi)" instruction as well: addi Rt Rs const a. [10 points] which existing components of the datapath are used for this instruction? What new functional components (if any) and/or control signals do we need for this instruction? b. [10 points Fill out control signal values in Figure 4.24 to support this instruction. RegDst ALUSrc MemtoReg RegWrite MemRead MemWrite Branch Jump ALUop

Explanation / Answer

Which exsisting components of the datapath are used for this instruction?
Existing blocks that can be used for this instruction are:
This instruction uses instruction memory, both existing read ports of Registers, the ALU, and
the write port of Registers.
This instruction uses the instruction memory, one of the existing register read ports, the path
that passed the immediate to the ALU, and the register write port.

wha new functional components or control signals do we need for this instruction
The new control signals are:
We need a control signal that tells the new ALU what to do, or if we extended the existing ALU we need to add a new ADD3 operation
We need to change the ALU Operation control signals to support the added SLL operation in the ALU.

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