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beautiful-racket/beautiful-racket-demo/hdl-demo/Dmux4Way.hdl.rkt

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910 B
Racket

#lang br/demo/hdl
// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/01/DMux4Way.hdl
/**
* 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 {
// todo: how should sel subscripting work?
IN in, sel[2];
OUT a, b, c, d;
PARTS:
DMux(in=in, sel=sel[0], a=a, b=b);
DMux(in=in, sel=sel[1], a=c, b=d);
/*
// the right answer: note that subscripting on right always means "read this bit";
// subscripting on left means "write this bit"
// build out assignment operator
DMux(in=in, sel=sel[0], a=s0a, b=s0b);
DMux(in=s0b, sel=sel[1], a=b, b=d);
DMux(in=s0a, sel=sel[1], a=a, b=c);
*/
}