Problem Set Number 6
Computer Science 471

Due by 5 PM, Monday Nov. 13, 2000

1. Exercise 6.9 from the text.

2. Exercise 6.19 from the text.

3. (counts as two questions) Exercise 6.20 from the text.

4. Exercise 6.22 from the text. In some printings, there is a misprint in the book: the reference to Exercise 3.23 should instead be to Exercise 3.17.

5. (counts as two questions) Figure 6.51 on page 499 has a serious problem that can easily be seen by altering the code sequence on page 498 so that the first instruction is

       sub  $3, $4, $8
and then checking the pipeline flow in Figure 6.52. What is the problem, and how would you fix it? Write a short explanation of the problem, and draw a picture like Figure 6.51, but make sure yours works, not just on the (altered) code sequence of page 498, but on any sequence of the MIPS subset instructions of this chapter. Consider both datapath (black elements of Figure 6.51) and control (green elements). Design for performance as well as correctness (e.g., two extra stalls may be correct but is not fast).