The ALU is controlled by the three wires F0, F1 and F2. These form a binary number between 0 and 7. Here is what they tell the ALU to put on its output wires:

F2 F1 F0
-------------------------------------------------------------
0  0  0     identity A     pass through A's value unchanged
0  0  1     identity TMP   pass through TMP's value unchanged
0  1  0     A and TMP      bitwise Boolean AND of A and TMP
0  1  1     A or TMP       bitwise Boolean OR of A and TMP
1  0  0     not TMP        bitwise Boolean NOT of TMP (A ignored)
1  0  1     A + TMP        arithmetic addition of A and TMP
1  1  0     A - TMP        arithmetic subtraction of A and TMP
1  1  1     unused