超星 - Ch4. Processor - 查题吧

简答题

The basic single-cycle MIPS implementation in Figure 4.2 （in the text book）can only implement some instructions. New instructions can be added to an existing Instruction Set Architecture (ISA), but the decision whether or not to do that depends, among other things, on the cost and complexity the proposed addition introduces into the processor data path and control. The first three problems in this exercise refer to the new instruction:Instruction: LWI Rt,Rd(Rs)Interpretation: Reg[Rt] = Mem[Reg[Rd]+Reg[Rs]]1 Which existing blocks (if any) can be used for this instruction?2 Which new functional blocks (if any) do we need for this instruction?3 What new signals do we need (if any) from the control unit to support this instruction?

简答题

For the problems in this exercise, assume that there are no pipeline stalls and that the breakdown of executed instructions is as follows:add addi not beq lwsw20% 20% 0% 25% 25% 10%1. In what fraction of all cycles is the data memory used?2. In what fraction of all cycles is the input of the sign-extend circuit needed? What is this circuit doing in cycles in which its input is not needed?

简答题

In this exercise we examine in detail how an instruction is executed in a single-cycle datapath. Problems in this exercise refer to a clock cycle in which the processor fetches the following instruction word:10101100011000100000000000010100.Assume that data memory is all zeros and that the processor’s registers have the following values at the beginning of the cycle in which the above instruction word is fetched:1.What are the outputs of the sign-extend and the jump “Shift left 2” unit (near the top of Figure 4.24 in the text book) for this instruction word?2. What are the values of the ALU control unit’s inputs for this instruction?3. What is the new PC address aft er this instruction is executed? Highlight the path through which this value is determined.4. For each Mux, show the values of its data output during the execution of this instruction and these register values.5. For the ALU and the two add units, what are their data input values?6. What are the values of all inputs for the “Registers” unit?

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