12
for class on
Monday
Nov. 8, 2010
Please read Section 4.5 of the text, which introduces the topic of pipelining.
Please turn in a written response to these questions:
1. Rather than jump right into a 5-stage pipelined design, let's look first at a simpler structure. Suppose you want to pipeline Chapter 4's single-cycle design (Figure 4.15, say) by dividing it into just two pipeline stages. You'll need a pipeline register (think laundry basket) to hold the first stage's results for the second stage. This pipeline register will be clocked at the same time as the PC, therby allowing two instructions to execute simultaneously. A first cut at a pipeline register for Figure 4.15 might just go straight down the middle, holding the following values from the first stage: PC+4, Register file outputs, sign-extended displacement, and function field. What would be one problem with this design?
2. What would be a second problem with this design?
Then, be prepared to discuss the following in class:
3. How could you address the two problems you identified above? You can move hardware around and add new hardware if you like.