44 lines
1.1 KiB
Plaintext
44 lines
1.1 KiB
Plaintext
// 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/DMux4Way.hdl
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/**
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* 4-way demultiplexor:
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* {a, b, c, d} = {in, 0, 0, 0} if sel == 00
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* {0, in, 0, 0} if sel == 01
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* {0, 0, in, 0} if sel == 10
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* {0, 0, 0, in} if sel == 11
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*/
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CHIP DMux4Way {
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IN in, sel[2];
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OUT a, b, c, d;
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PARTS:
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/**
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* Demultiplexor:
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* {x, y} = {in, 0} if sel[0] == 0
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* {0, in} if sel[0] == 1
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*/
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DMux(in=in, sel=sel[0], a=x, b=y);
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// Now we can copy x,y to abcd as {x|0,y|0,x|0,y|0}
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// depending on sel[1]
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// sel| 00 | 01 || 10 | 11
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//S[1]| 0 || 1
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//----|----|----||----|---
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// x | in | 0 || in | 0
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// y | 0 | in || 0 | in
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//----|----|----||----|---
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// a | in | 0 || 0 | 0
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// b | 0 | in || 0 | 0
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// c | 0 | 0 || in | 0
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// d | 0 | 0 || 0 | in
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Mux(a=x, b=false, sel=sel[1], out=a);
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Mux(a=y, b=false, sel=sel[1], out=b);
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Mux(a=false, b=x, sel=sel[1], out=c);
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Mux(a=false, b=y, sel=sel[1], out=d);
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}
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