4wayDemux

// This file is part of the materials accompanying the book
// "The Elements of Computing Systems" by Nisan and Schocken,
// MIT Press. Book site: www.idc.ac.il/tecs
// File name: projects/01/DMux4Way.hdl

/**
 * 4-way demultiplexor.  The 2-bit sel input selects the output to which
 * the in input will be channeled: 00 to a, 01 to b, 10 to c, 11 to d.
 * The other outputs are set to 0.
 */

CHIP DMux4Way {

    IN  in, sel[2];
    OUT a, b, c, d;

    PARTS:
    Not(in=sel[0], out=ns0);
    Not(in=sel[1], out=ns1);

    And(a=sel[0], b=sel[1], out=s1);
    And(a=ns0, b=sel[1], out=ns);
    And(a=sel[0], b=ns1, out=sn);
    And(a=ns0, b=ns1, out=s0);

    And(a=in, b=s0, out=a);
    And(a=in, b=ns, out=c);
    And(a=in, b=sn, out=b);
    And(a=in, b=s1, out=d);
}