13
for class on
Wednesday
Nov. 7, 2012
Please read Section 4.6 of the Patterson & Hennessy text.
Please turn in written responses to these questions:
1. Use colored pens or markers to show which portions of the datapath of Figure 4.35 are active in each of the five stages of the add instruction. Do this in the style of Figures 4.36 through 4.38, using this page, which contains five tiny copies of Figure 4.35. Color the tiny copies appropriately, and use top-to-bottom order for your steps rather than left-to-right.
2.
The control circuitry for the five-stage MIPS pipeline of the text
must somehow be equivalent to one or more finite-state machines,
since any sequential, deterministic device made of
a finite collection of parts can be described as one or more
finite-state machines. Do you think it's one or more than one? Write say two sentences to support your view.
Then, be prepared to discuss the following in class:
3. It seems as if there might be a very large number of states with complicated state-transition rules: after all, there are lots and lots of combinations of instructions that could potentially occupy the five different pipeline stages in the same cycle. How would you describe the finite-state machine or machines, and how would you specify the states and the state-transition function or functions? (We'll be operating at the circles-and-arrows level for most of this class.)
