$.$ In Logisim, using your adder, the mux$$s you built $($as many copies of these as you need$),$ and AND, OR$,$ and NOT gates, create a $4-$bit ALU that performs AND, OR$,+$ and $-.$ It should have the following inputs: a$0,$ a$1,$ a$2,$ a$3,$ b$0,$ b$1,$ b$2,$ b$3,$ control$0,$ and control$1.$ It should have following outputs: res$0,$ res$1,$ res$2,$ res$3,$ and carry$\_$out. The two control lines should determine the operation to be performed as follows:

control$1$ control$0$

$00$ AND

$01$ OR

$10+$

$11-$

Note that this ALU will be slightly different from the ALU in the class notes, since there is no separate Binvert line. Note: To incorporate previously$-$built circuits in a circuit, click $$Project $>$ Load Library $>$ Logisim$-$evolution Library...$$ and then choose the file you had saved. On the left hand side, a new folder will appear with the name of the file. Double$-$click on the folder and you should see a circuit with the name you gave it$.$ It will be represented as a rectangle with inputs $($small dots$)$ on the left and outputs $($also small dots$)$ on the right. Select and use the circuit just as you would any other device $($e$.$g$.$ AND gate$).$ Be sure to add text to label the devices.