No more secrets Part D: Here is the ALU: all together now!
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The entire ALU is now able to perform many different computations:
F1 F0 enA enB invB Cin Sign Result 0 1 0 0 0 x x 0 1 0 0 0 0 1 x 1 0 1 0 0 1 x x -1 (all output bits are set to one) 0 1 1 0 0 x x A 0 1 0 1 0 x x B 0 1 0 1 1 x x not B 0 0 1 1 0 x x A and B (bitwise) 0 1 1 1 0 x x A or B (bitwise) 0 0 1 1 1 x x A and not B (bitwise) 0 1 1 1 1 x x A or not B (bitwise) 1 0 1 1 0 0 0/1 A + B 1 0 1 1 1 1 0/1 A - B 1 0 1 0 0 1 0/1 A + 1 1 0 1 0 1 0 0/1 A - 1 1 1 1 1 1 1 0/1 1 if A<B, 0 otherwise 1 1 1 0 1 1 0/1 1 if A<0, 0 otherwise 1 1 0 1 1 1 0/1 1 if B>0, 0 otherwise