An ALU is really two units in one -- there’s an arithmetic unit and a logic unit.
the pièce de résistance, the crème de la crème of operations - adding two numbers together.
-circuit
-AND, OR, NOT and XOR gates.
another level of abstraction…
sum and carry.
overflow.
the Logic Unit - AND, OR and NOT
checking negative, zero, overflow...
the 74181 could only handle 4-bit inputs
