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+# ignore nand2tetris testing files
+projects/*/*.cmp
+projects/*/*.tst
+projects/*/*.out
+

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+// 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/And.hdl
+
+/**
+ * And gate: 
+ * out = 1 if (a == 1 and b == 1)
+ *       0 otherwise
+ */
+
+CHIP And {
+    IN a, b;
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/And16.hdl
+
+/**
+ * 16-bit bitwise And:
+ * for i = 0..15: out[i] = (a[i] and b[i])
+ */
+
+CHIP And16 {
+    IN a[16], b[16];
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/DMux.hdl
+
+/**
+ * Demultiplexor:
+ * {a, b} = {in, 0} if sel == 0
+ *          {0, in} if sel == 1
+ */
+
+CHIP DMux {
+    IN in, sel;
+    OUT a, b;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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 {
+    IN in, sel[2];
+    OUT a, b, c, d;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/DMux8Way.hdl
+
+/**
+ * 8-way demultiplexor:
+ * {a, b, c, d, e, f, g, h} = {in, 0, 0, 0, 0, 0, 0, 0} if sel == 000
+ *                            {0, in, 0, 0, 0, 0, 0, 0} if sel == 001
+ *                            etc.
+ *                            {0, 0, 0, 0, 0, 0, 0, in} if sel == 111
+ */
+
+CHIP DMux8Way {
+    IN in, sel[3];
+    OUT a, b, c, d, e, f, g, h;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Mux.hdl
+
+/** 
+ * Multiplexor:
+ * out = a if sel == 0
+ *       b otherwise
+ */
+
+CHIP Mux {
+    IN a, b, sel;
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Mux16.hdl
+
+/**
+ * 16-bit multiplexor: 
+ * for i = 0..15 out[i] = a[i] if sel == 0 
+ *                        b[i] if sel == 1
+ */
+
+CHIP Mux16 {
+    IN a[16], b[16], sel;
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Mux4Way16.hdl
+
+/**
+ * 4-way 16-bit multiplexor:
+ * out = a if sel == 00
+ *       b if sel == 01
+ *       c if sel == 10
+ *       d if sel == 11
+ */
+
+CHIP Mux4Way16 {
+    IN a[16], b[16], c[16], d[16], sel[2];
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Mux8Way16.hdl
+
+/**
+ * 8-way 16-bit multiplexor:
+ * out = a if sel == 000
+ *       b if sel == 001
+ *       etc.
+ *       h if sel == 111
+ */
+
+CHIP Mux8Way16 {
+    IN a[16], b[16], c[16], d[16],
+       e[16], f[16], g[16], h[16],
+       sel[3];
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Not.hdl
+
+/**
+ * Not gate:
+ * out = not in
+ */
+
+CHIP Not {
+    IN in;
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Not16.hdl
+
+/**
+ * 16-bit Not:
+ * for i=0..15: out[i] = not in[i]
+ */
+
+CHIP Not16 {
+    IN in[16];
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Or.hdl
+
+ /**
+ * Or gate:
+ * out = 1 if (a == 1 or b == 1)
+ *       0 otherwise
+ */
+
+CHIP Or {
+    IN a, b;
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Or16.hdl
+
+/**
+ * 16-bit bitwise Or:
+ * for i = 0..15 out[i] = (a[i] or b[i])
+ */
+
+CHIP Or16 {
+    IN a[16], b[16];
+    OUT out[16];
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Or8Way.hdl
+
+/**
+ * 8-way Or: 
+ * out = (in[0] or in[1] or ... or in[7])
+ */
+
+CHIP Or8Way {
+    IN in[8];
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}

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+// 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/Xor.hdl
+
+/**
+ * Exclusive-or gate:
+ * out = not (a == b)
+ */
+
+CHIP Xor {
+    IN a, b;
+    OUT out;
+
+    PARTS:
+    // Put your code here:
+}