DMux4Way

1對4 DMux，1條資料線，2條選擇線，a,b,c,d 4條輸出線。

    | in  | sel  |  a  |  b  |  c  |  d  |
    |  0  |  00  |  0  |  0  |  0  |  0  |
    |  0  |  01  |  0  |  0  |  0  |  0  |
    |  0  |  10  |  0  |  0  |  0  |  0  |
    |  0  |  11  |  0  |  0  |  0  |  0  |
    |  1  |  00  |  1  |  0  |  0  |  0  |
    |  1  |  01  |  0  |  1  |  0  |  0  |
    |  1  |  10  |  0  |  0  |  1  |  0  |
    |  1  |  11  |  0  |  0  |  0  |  1  |


    /**
     * 4-way demultiplexor:
     * {a, b, c, d} = {in, 0, 0, 0} if sel == 00
     *                {0, in, 0, 0} if sel == 01
     *                {0, 0, in, 0} if sel == 10
     *                {0, 0, 0, in} if sel == 11
     */

CHIP DMux4Way 
        {
                IN in, sel[2];
                OUT a, b, c, d;

                PARTS:
                DMux(in = in, sel = sel[0], a = a);
                DMux(in = in, sel = sel[1], a = b);
                DMux(in = in, sel = sel[2], a = c);
                DMux(in = in, sel = sel[3], a = d);
         }