42 lines
1.2 KiB
VHDL
42 lines
1.2 KiB
VHDL
// This file is part of www.nand2tetris.org
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// and the book "The Elements of Computing Systems"
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// by Nisan and Schocken, MIT Press.
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// File name: projects/01/DMux8Way.hdl
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/**
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* 8-way demultiplexor:
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* {a, b, c, d, e, f, g, h} = {in, 0, 0, 0, 0, 0, 0, 0} if sel == 000
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* {0, in, 0, 0, 0, 0, 0, 0} if sel == 001
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* etc.
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* {0, 0, 0, 0, 0, 0, 0, in} if sel == 111
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*/
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// COST = 37 + 8*8 = 101
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CHIP DMux8Way {
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IN in, sel[3];
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OUT a, b, c, d, e, f, g, h;
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PARTS:
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// This makes our "repeated building block" - which we repeat twice
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// Same as how we do it in DMux4Way
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DMux4Way(in=in, sel[0]=sel[0], sel[1]=sel[1], a=w, b=x, c=y, d=z);
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// If sel[2] is 1:
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// set a,b,c,d to 0
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// else set a,b,c,d to w,x,y,z
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Mux(a=w, b=false, sel=sel[2], out=a);
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Mux(a=x, b=false, sel=sel[2], out=b);
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Mux(a=y, b=false, sel=sel[2], out=c);
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Mux(a=z, b=false, sel=sel[2], out=d);
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// If sel[2] is 0:
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// set e,f,g,h to 0
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// else set e,f,g,h to w,x,y,z
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Mux(a=false, b=w, sel=sel[2], out=e);
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Mux(a=false, b=x, sel=sel[2], out=f);
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Mux(a=false, b=y, sel=sel[2], out=g);
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Mux(a=false, b=z, sel=sel[2], out=h);
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}
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