1. Basic Pipeline Datapath

2. Pipeline In Use
We’ll follow two instructions through the pipeline, first separately, then together.
add $7,$2,$3, where $2 = 35 and $3 = 62
lw $4, 28($5), where $5=56 and memory location 84 stores 20
add instruction at location 40; lw at 44
Note: rightmost multiplexor is inverted

3. add $7,$2,$3 – IF stage 40 44 40
add

4. add $7,$2,$3 – ID stage 10
000
000000
1100 2 35 3 62
100000 7

5. add $7,$2,$3 – EX stage 10
000 35 62 97 1
0010 62
100000 10 7 7 1

6. add $7,$2,$3 – MEM stage 10 97 7

7. add $7,$2,$3 – WB stage 1 7 97 97

8. lw $4, 28($5) – IF stage 44 48 44 lw

9. lw $4, 28($5) – ID stage 11
010
100011
0001 5 56 28 4

10. lw $4, 28($5)– EX stage 11
010 56 1 84 1
0010 28 28 4 00 4

11. lw $4, 28($5)–– MEM stage 11 84 20 1 4

12. lw $4, 28($5)–– WB stage 1 1 20 4 20

13. add – IF stage 40 44 40
add

14. lw – IF stage, add – ID stage10
000
000000
1100 44 48 2 35 44 3 62 lw
100000 7

15. lw – ID stage, add – EX stage11 10
010
100011
000
0001 5 56 35 62 97
0010 62 28
100000 4 10 7 7 1

16. lw – EX stage, add – MEM stage11
010 10 56 1 84 1
0010 28 28 97 4 00 4 7

17. lw – MEM stage, add – WB stage11 1 84 20 7 97 97 1 4

18. lw - WB stage 1 1 20 4 20