Consider two computer systems A and B. For A, a branch is implemented by two instructions:
Sub $3, $1, $2 #$3=$1-$2
Branch $3, 300 #take the branch if $3=0
For B, the compare is included in the branch instruction as in our MIPS architecture
Beq, $1, $2, 300
All other instructions of the two machines are the same and on both machines, the instructions take the same number of cycles. The instruction frequency of machine A is shown in the following table. Since in a single instruction, machine B has to test the condition as well as handle the branch, the cycle time of machine B is 25% longer than A.
Instruction type
% Clock cycle count ALU ops
47% 1 Loads
21% 2 Stores
12% 2 Branches
20% 2
(1) What is CPI of A? CPI of B?
(2) Execution time of A?
(3) Execution time of B?
(4) Which one if faster? By how much?

Hi Ginwah,

Sorry but you have to do a little better than that. Do you know what CPI is?

I know the first answer:
CPI of A = 0.47 + (2 x 0.21) + (2 x 0.12) + (2 x 0.2)
But what about CPI of B?