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Let's calculate the number of cycles each instruction takes before reaching the ' sw ' instruction for the first loop iteration and find the corresponding

Let's calculate the number of cycles each instruction takes before reaching the 'sw' instruction for the first loop iteration and find the corresponding PC value.
Here's the instruction breakdown with their cycle counts:
1. add TO, zero, zero =>4 cycles
2. add T1, R1, zero =>4 cycles
3. add T2, R2, zero =>4 cycles
4. Loop: lw T4,0(T2)=>5 cycles
5. add T5, T4, C =>4 cycles
6. sw T5,0(T1)=>4 cycles (the one we need to calculate the PC for)
Now, we add up the cycles before the 'sw' operation:
4(add TO)+4(add T1)+4(add T2)+5(lw T4)+4(add T5)=21 cycles
If we're given PC value increments of 4, which is typical in MIPS (as most instructions are 4 bytes), and we know the loop starts at an initial PC value of 120, we can calculate the PC value for the 'sw' instruction as follows:
Starting PC =120
PC after 1st instruction (add TO)=120+4=124
PC after 2nd instruction (add T1)=124+4=128
PC after 3rd instruction (add T2)=128+4=132
PC for lw instruction (4th)=132+4=136
PC for the 'sw' instruction (6th) is the one after the 'add T5' so:
PC for 'add T5'(5th)=136+4=140
PC for 'sw' T5(6th)=140+4=144
Therefore, the correct answer is:
PC value for the SW instruction =144.

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