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sorry, you are absoulely right!!
I'm isreali... and i learn your course nand to tetris by onkine course in campus called "campus il" by Shion shoken and.. i wrote their the chip 'alu' without zr.... just the beggining.
i add now all my implemented.
this is one of the foles of nand to tetris, and i check it with the script nonstat.. that i got from you.
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/02/ALU.hdl
/**
* The ALU (Arithmetic Logic Unit).
* 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,
* according to 6 input bits denoted zx,nx,zy,ny,f,no.
* In addition, the ALU computes two 1-bit outputs:
* if the ALU output == 0, zr is set to 1; otherwise zr is set to 0;
* if the ALU output < 0, ng is set to 1; otherwise ng is set to 0.
*/
// Implementation: the ALU logic manipulates the x and y inputs
// and operates on the resulting values, as follows:
// if (zx == 1) set x = 0 // 16-bit constant
// if (nx == 1) set x = !x // bitwise not
// if (zy == 1) set y = 0 // 16-bit constant
// if (ny == 1) set y = !y // bitwise not
// if (f == 1) set out = x + y // integer 2's complement addition
// if (f == 0) set out = x & y // bitwise and
// if (no == 1) set out = !out // bitwise not
// if (out == 0) set zr = 1
// if (out < 0) set ng = 1
CHIP ALU {
IN
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 1) or x & y (if 0)
no; // negate the out output?
OUT
out[16], // 16-bit output
zr, // 1 if (out == 0), 0 otherwise
ng; // 1 if (out < 0), 0 otherwise
PARTS:
Mux16(a=x,b=false,sel=zx,out=x1);
Mux16(a=y,b=false,sel=zy,out=y1);
Not16(in=x1,out=nx1);
Mux16(a=x1,b=nx1,sel=nx,out=x2);
Not16(in=y1,out=ny1);
Mux16(a=y1,b=ny1,sel=ny,out=y2);
Add16(a=x2,b=y2,out=aPlusB);
And16(a=x2,b=y2,out=aAndb);
Mux16(a=aAndb,b=aPlusB,sel=f,out=out0);
Not16(in=out0,out=nout0);
Mux16(a=out0,b=nout0,sel=no,out=out);
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