Quiz submission record for quiz6-1-1 at Mon Jul 26 09:36:57 2004:

Your Answer for Question 1:
You need to pipeline the control as well because the control lines are inherently related to the datapath.  In fact, pipelining the datapath does NOT change the meaning of the control lines; it merely groups them by pipeline stage.  Without pipelining the control lines, then, it would be possible to have misalligned control lines - that is, each stage in the pipeline may or may not get the control signals it needs and instead they may all be concentrated at the ID/EX stage.

Your Answer for Question 2:
The three values are coming from 
- a forwarded value (from after the Memory/WB stage)
      lw $t1, 0($t2)
      add $t5, $t1, $t5
      (second add has to wait until after memory is
       accessed to ensure that it gets the correct
       value for $t1)
 - a forwarded value (from after the ALU/execute   stage)
     add $t1, $t2, $t3
     add $t5, $t1, $t2
     (second add needs $t1 from first add, which is
      ready after the ALU stage and $t2+$t3 has
      occured)
- a value that is read from the register
     add $t1, $t2, $t3
     add $t4, $t5, $t3
     (RAR, can use values coming from register)

Your Answer for Question 3:
The hazard unit inserts bubbles by stalling the instruction 1 clock cycle or by deasserting all nine control signals (depending on which stage the stall occurs).


Your unique submission ID is quiz6-1-1-cs61c-ax-1090859817-2949.