/**
 * Multiplexor:
 * out = a if sel == 0
 *       b otherwise
 */

CHIP Mux {
    IN a, b, sel;
    OUT out;

    PARTS:
    Nand(a=b, b=sel, out = out1);
    Nand(a=sel, b=sel, out = out2);
    Nand(a=out2, b=a, out = out3);
    Nand(a=out1, b=out3, out = out);
}