Quiz submission record for quiz5-1-1 at Mon Jul 19 00:56:25 2004:

Your Answer for Question 1:
All instruction classes use reading from the registers and the ALU. This is where the simplicity and regularity pays off, because being able to process all instructions using a single or small variety of units surely reduce size, cost, and complexity. However, after using the ALU, different instructions require different actions.

Your Answer for Question 2:
When writing data on a register (after the execution of an instruction), this RegWrite signal controls whether it will be proceeded or not. When it is asserted, the register unit goes ahead and write on the specified register at the clock edge.

Your Answer for Question 3:
The purpose of the Add unit is to compute the branch target, which is the sum of PC + 4 and lower 16 bits of the instruction after it has been sign-extended and shift left two bits. It would be possible to use ALU for the functions of both ALU and Adder, if we implemented a multiplexor for each of its input and output and delayed one operation so that it is performed after another. But we would be risking serious slowdown in speed, because these operations can be, with both ALU and Adder, performed simultaneously.


Your unique submission ID is quiz5-1-1-cs61c-ew-1090223785-1904.