Sample Final/Problem01

Problem 1. [10 points] Tomasulo’s Algorithm

This problem is about a processor that uses Tomasulo’s algorithm (no ROB), with a total of 3 reservation stations. Any instruction can use any reservation station. The processor is 1-wide. Do not make any assumptions about the execution latencies of particular instructions. The current state of reservation stations is:

resStation.jpg

  1. [2 points] What was the order in which these three instructions were issued?

  2. [2 points] Let X be the number of instructions that are currently being executed. From the given current state of the reservation stations, what can we infer about X?

  3. [2 points] When the MUL instruction broadcasts its result on the CDB, what data value and tag (name) will it put on the CDB?

  4. [2 points] When the ADD instruction broadcasts its result on the CDB, what data value and tag (name) will it put on the CDB?

  5. [1 points] True or False (circle the correct answer): We can say for sure that one of these three instructions was the last instruction issued by this processor thus far.

  6. [1 points] True or False (circle the correct answer): It is possible that these are not the last three instructions issued by this processor thus far.