error message "A pin name is expected" when testing the ALU

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error message "A pin name is expected" when testing the ALU

I've built my ALU, but whenever I try to load it into the Hardware Simulator I get the error message:
"In HDL file C:\nand2tetris\nand2tetris\projects\02\ALU.hdl, line 51, a pin name is expected."
line 51 is the first component of my ALU, a Mux:
    Mux(a=x[0], b=zero, sel=zx, out=1x0);
To my understanding, the error message implies that this line is missing some component pin, but i can't figure out where I went wrong.  The only thing I can think of is the b=zero component, since I did not define what "zero" is, but that should default the value to 0 (since it's an unconnected input pin).  Ive also tried explicitly defining "zero" by adding this Xor:
    Xor(a=x[0], b=x[0], out=zero);
but this changed nothing.
Here's my full ALU:
// This file is part of
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/02/ALU.hdl

 * The ALU. Computes one of the following functions:
 * x+y, x-y, y–x, 0, 1, -1, x, y, -x, -y, !x, !y,
 * x+1, y+1, x-1, y-1, x&y, x|y on two 16-bit inputs.
 * Which function to compute is determined by 6 input bits
 * denoted zx, nx, zy, ny, f, no.
 * The computed function's value is called "out".
 * In addition to computing out, the ALU computes two
 * 1-bit outputs called zr and ng:
 * if out == 0, zr = 1; otherwise zr = 0;
 * If out < 0, ng = 1; otherwise ng = 0.
 * The 6-bit combinations (zx,nx,zy,ny,f,no) and
 * their effect are documented in the book.

// Implementation: the ALU manipulates the x and y
// inputs and then operates on the resulting values,
// as follows:
// if (zx  == 1) sets x = 0        // 16-bit constant
// if (nx  == 1) sets x = ~x       // bitwise "not"
// if (zy  == 1) sets y = 0        // 16-bit constant
// if (ny  == 1) sets y = ~y       // bitwise "not"
// if (f   == 1) sets out = x + y  // integer 2's-complement addition
// if (f   == 0) sets out = x & y  // bitwise And
// if (no  == 1) sets out = ~out   // bitwise Not
// if (out == 0) sets zr = 1
// if (out < 0)  sets ng = 1

        x[16], y[16],  // 16-bit inputs        
        zx, // zero the x input?
        nx, // negate the x input?
        zy, // zero the y input?
        ny, // negate the y input?
        f,  // compute  out = x + y (if f == 1) or out = x & y (if == 0)
        no; // negate the out output?

        out[16], // 16-bit output
        zr, // 1 if (out == 0), 0 otherwise
        ng; // 1 if (out < 0),  0 otherwise

    Mux(a=x[0], b=zero, sel=zx, out=1x0);
    Mux(a=x[1], b=zero, sel=zx, out=1x1);
    Mux(a=x[2], b=zero, sel=zx, out=1x2);
    Mux(a=x[3], b=zero, sel=zx, out=1x3);
    Mux(a=x[4], b=zero, sel=zx, out=1x4);
    Mux(a=x[5], b=zero, sel=zx, out=1x5);
    Mux(a=x[6], b=zero, sel=zx, out=1x6);
    Mux(a=x[7], b=zero, sel=zx, out=1x7);
    Mux(a=x[8], b=zero, sel=zx, out=1x8);
    Mux(a=x[9], b=zero, sel=zx, out=1x9);
    Mux(a=x[10], b=zero, sel=zx, out=1x10);
    Mux(a=x[11], b=zero, sel=zx, out=1x11);
    Mux(a=x[12], b=zero, sel=zx, out=1x12);
    Mux(a=x[13], b=zero, sel=zx, out=1x13);
    Mux(a=x[14], b=zero, sel=zx, out=1x14);
    Mux(a=x[15], b=zero, sel=zx, out=1x15);
    Xor(a=1x0, b=nx, out=2x0);
    Xor(a=1x1, b=nx, out=2x1);
    Xor(a=1x2, b=nx, out=2x2);
    Xor(a=1x3, b=nx, out=2x3);
    Xor(a=1x4, b=nx, out=2x4);
    Xor(a=1x5, b=nx, out=2x5);
    Xor(a=1x6, b=nx, out=2x6);
    Xor(a=1x7, b=nx, out=2x7);
    Xor(a=1x8, b=nx, out=2x8);
    Xor(a=1x9, b=nx, out=2x9);
    Xor(a=1x10, b=nx, out=2x10);
    Xor(a=1x11, b=nx, out=2x11);
    Xor(a=1x12, b=nx, out=2x12);
    Xor(a=1x13, b=nx, out=2x13);
    Xor(a=1x14, b=nx, out=2x14);
    Xor(a=1x15, b=nx, out=2x15);
    Mux(a=y[0], b=zero, sel=zy, out=1y0);
    Mux(a=y[1], b=zero, sel=zy, out=1y1);
    Mux(a=y[2], b=zero, sel=zy, out=1y2);
    Mux(a=y[3], b=zero, sel=zy, out=1y3);
    Mux(a=y[4], b=zero, sel=zy, out=1y4);
    Mux(a=y[5], b=zero, sel=zy, out=1y5);
    Mux(a=y[6], b=zero, sel=zy, out=1y6);
    Mux(a=y[7], b=zero, sel=zy, out=1y7);
    Mux(a=y[8], b=zero, sel=zy, out=1y8);
    Mux(a=y[9], b=zero, sel=zy, out=1y9);
    Mux(a=y[10], b=zero, sel=zy, out=1y10);
    Mux(a=y[11], b=zero, sel=zy, out=1y11);
    Mux(a=y[12], b=zero, sel=zy, out=1y12);
    Mux(a=y[13], b=zero, sel=zy, out=1y13);
    Mux(a=y[14], b=zero, sel=zy, out=1y14);
    Mux(a=y[15], b=zero, sel=zy, out=1y15);
    Xor(a=1y0, b=ny, out=2y0);
    Xor(a=1y1, b=ny, out=2y1);
    Xor(a=1y2, b=ny, out=2y2);
    Xor(a=1y3, b=ny, out=2y3);
    Xor(a=1y4, b=ny, out=2y4);
    Xor(a=1y5, b=ny, out=2y5);
    Xor(a=1y6, b=ny, out=2y6);
    Xor(a=1y7, b=ny, out=2y7);
    Xor(a=1y8, b=ny, out=2y8);
    Xor(a=1y9, b=ny, out=2y9);
    Xor(a=1y10, b=ny, out=2y10);
    Xor(a=1y11, b=ny, out=2y11);
    Xor(a=1y12, b=ny, out=2y12);
    Xor(a=1y13, b=ny, out=2y13);
    Xor(a=1y14, b=ny, out=2y14);
    Xor(a=1y15, b=ny, out=2y15);
    HalfAdd(a=2x0, b=2y0, sum=sum0, carry=carry1);
    FullAdd(a=2x1, b=2y1, c=carry1, sum=sum1, carry=carry2);
    FullAdd(a=2x2, b=2y2, c=carry2, sum=sum2, carry=carry3);
    FullAdd(a=2x3, b=2y3, c=carry3, sum=sum3, carry=carry4);
    FullAdd(a=2x4, b=2y4, c=carry4, sum=sum4, carry=carry5);
    FullAdd(a=2x5, b=2y5, c=carry5, sum=sum5, carry=carry6);
    FullAdd(a=2x6, b=2y6, c=carry6, sum=sum6, carry=carry7);
    FullAdd(a=2x7, b=2y7, c=carry7, sum=sum7, carry=carry8);
    FullAdd(a=2x8, b=2y8, c=carry8, sum=sum8, carry=carry9);
    FullAdd(a=2x9, b=2y9, c=carry9, sum=sum9, carry=carry10);
    FullAdd(a=2x10, b=2y10, c=carry10, sum=sum10, carry=carry11);
    FullAdd(a=2x11, b=2y11, c=carry11, sum=sum11, carry=carry12);
    FullAdd(a=2x12, b=2y12, c=carry12, sum=sum12, carry=carry13);
    FullAdd(a=2x13, b=2y13, c=carry13, sum=sum13, carry=carry14);
    FullAdd(a=2x14, b=2y14, c=carry14, sum=sum14, carry=carry15);
    FullAdd(a=2x15, b=2y15, c=carry15, sum=sum15, carry=carry16);
    And(a=2x0, b=2y0, out=and0);
    And(a=2x1, b=2y1, out=and1);
    And(a=2x2, b=2y2, out=and2);
    And(a=2x3, b=2y3, out=and3);
    And(a=2x4, b=2y4, out=and4);
    And(a=2x5, b=2y5, out=and5);
    And(a=2x6, b=2y6, out=and6);
    And(a=2x7, b=2y7, out=and7);
    And(a=2x8, b=2y8, out=and8);
    And(a=2x9, b=2y9, out=and9);
    And(a=2x10, b=2y10, out=and10);
    And(a=2x11, b=2y11, out=and11);
    And(a=2x12, b=2y12, out=and12);
    And(a=2x13, b=2y13, out=and13);
    And(a=2x14, b=2y14, out=and14);
    And(a=2x15, b=2y15, out=and15);
    Dmux(a=and0, b=sum0, sel=f, out=almost0);
    Dmux(a=and1, b=sum1, sel=f, out=almost1);
    Dmux(a=and2, b=sum2, sel=f, out=almost2);
    Dmux(a=and3, b=sum3, sel=f, out=almost3);
    Dmux(a=and4, b=sum4, sel=f, out=almost4);
    Dmux(a=and5, b=sum5, sel=f, out=almost5);
    Dmux(a=and6, b=sum6, sel=f, out=almost6);
    Dmux(a=and7, b=sum7, sel=f, out=almost7);
    Dmux(a=and8, b=sum8, sel=f, out=almost8);
    Dmux(a=and9, b=sum9, sel=f, out=almost9);
    Dmux(a=and10, b=sum10, sel=f, out=almost10);
    Dmux(a=and11, b=sum11, sel=f, out=almost11);
    Dmux(a=and12, b=sum12, sel=f, out=almost12);
    Dmux(a=and13, b=sum13, sel=f, out=almost13);
    Dmux(a=and14, b=sum14, sel=f, out=almost14);
    Dmux(a=and15, b=sum15, sel=f, out=almost15);
    Not(in=almost0, out=notout0);
    Not(in=almost1, out=notout1);
    Not(in=almost2, out=notout2);
    Not(in=almost3, out=notout3);
    Not(in=almost4, out=notout4);
    Not(in=almost5, out=notout5);
    Not(in=almost6, out=notout6);
    Not(in=almost7, out=notout7);
    Not(in=almost8, out=notout8);
    Not(in=almost9, out=notout9);
    Not(in=almost10, out=notout10);
    Not(in=almost11, out=notout11);
    Not(in=almost12, out=notout12);
    Not(in=almost13, out=notout13);
    Not(in=almost14, out=notout14);
    Not(in=almost15, out=notout15);
    Dmux(a=almost0, b=notout0, sel=no, out=out[0]);
    Dmux(a=almost1, b=notout1, sel=no, out=out[1]);
    Dmux(a=almost2, b=notout2, sel=no, out=out[2]);
    Dmux(a=almost3, b=notout3, sel=no, out=out[3]);
    Dmux(a=almost4, b=notout4, sel=no, out=out[4]);
    Dmux(a=almost5, b=notout5, sel=no, out=out[5]);
    Dmux(a=almost6, b=notout6, sel=no, out=out[6]);
    Dmux(a=almost7, b=notout7, sel=no, out=out[7]);
    Dmux(a=almost8, b=notout8, sel=no, out=out[8]);
    Dmux(a=almost9, b=notout9, sel=no, out=out[9]);
    Dmux(a=almost10, b=notout10, sel=no, out=out[10]);
    Dmux(a=almost11, b=notout11, sel=no, out=out[11]);
    Dmux(a=almost12, b=notout12, sel=no, out=out[12]);
    Dmux(a=almost13, b=notout13, sel=no, out=out[13]);
    Dmux(a=almost14, b=notout14, sel=no, out=out[14]);
    Dmux(a=almost15, b=notout15, sel=no, out=out[15]);
    Or(a=out[0], b=out[1], out=1nzr);
    Or(a=1nzr, b=out[2], out=2nzr);
    Or(a=2nzr, b=out[3], out=3nzr);
    Or(a=3nzr, b=out[4], out=4nzr);
    Or(a=4nzr, b=out[5], out=5nzr);
    Or(a=5nzr, b=out[6], out=6nzr);
    Or(a=6nzr, b=out[7], out=7nzr);
    Or(a=7nzr, b=out[8], out=8nzr);
    Or(a=8nzr, b=out[9], out=9nzr);
    Or(a=9nzr, b=out[10], out=10nzr);
    Or(a=10nzr, b=out[11], out=11nzr);
    Or(a=11nzr, b=out[12], out=12nzr);
    Or(a=12nzr, b=out[13], out=13nzr);
    Or(a=13nzr, b=out[14], out=14nzr);
    Or(a=14nzr, b=out[15], out=ng);
    Not(in=ng, out=zr);

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Re: error message "A pin name is expected" when testing the ALU

You want to use the built-in constant "false".

This is an extremely hard way to write the ALU. There is a reason why you have been building 16-bit wide chips.


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Re: error message "A pin name is expected" when testing the ALU

Changing "zero" to "false" doesn't change the error message that I get.
I realize now how to do the ALU more easily with the 16-bit chips, but I wasn't sure of how to do the syntax correctly at first so I built it all out of 1-bit chips.  I could probably do it over with 16-bit chips, but I wanted to see if this implementation worked first (which is where I ran into the error message).
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Re: error message "A pin name is expected" when testing the ALU

Sorry, I missed the forest for the trees. The error is caused by the pin name '1x0'. Pin names must start with a letter.

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Re: error message "A pin name is expected" when testing the ALU

Ah, thanks!
I ended up following your advice and redoing the ALU with 16-bit chips anyway since there were more errors with this implementation besides the pin name.