Quiz submission record for quiz6-1-1 at Mon Jul 26 09:52:16 2004:

Your Answer for Question 1:
Then the execution of code will get all jumbled up together and you will not get the behavior you desired. For example, PC would be incrementing by 4 even when the branch should have been taken (which will notify the PC Mux after EX/MEM stage), so in this case two unnecessary instructions will be processed. Another instance would be read after write data dependency. For instructions like add $1, $2, $3 and add $4, $1, $1, the register $1's value is not settled until the WB stage, so the second instruction will be using $1's old value instead of the new. Store and load instructions in a row present the similar problem.

Your Answer for Question 2:
ForwardA's three possible values are 00(meaning that the first ALU operand comes from the register file), 10(is forwarded from the prior ALU result), and 01(is forwarded from data memory or an earlier ALU result). 
Examples,
nop => nop => nop => add $1, $2, $3 => picks 00.
nop => nop => add $1, $2, $3 => add $4, $1, $1 => picks 10.
nop => nop => lw $1, 0($2) => add $3, $1, $1 => picks 01.

Your Answer for Question 3:
To insert bubbles, the hazard unit forces stages of the following pipelined instructions to repeat. Such repeated work is what a stall looks like, but it simply delays the following pipelined instrcutions from advancing forward.
What prevents the hazard unit from inserting the same bubble over and over and over is that there is no need for such thing. The most traumatic hazard generators like branching and reading after loading only requires only one bubble to be inserted in following instructions.


Your unique submission ID is quiz6-1-1-cs61c-ew-1090860736-516.