/**
 * Exclusive-or gate:
 * out = not (a == b)
 */

CHIP Xor {
    IN a, b;
    OUT out;

    PARTS:
    Nand(a=a, b=b, out = i);

    Nand(a=a, b=a, out = na);
    Nand(a=b, b=b, out = nb);
    Nand(a=na, b=nb, out = j);

    Nand(a = i, b = j, out = q);
    Nand(a = q, b = q, out = out);
}