Confused why ALU implementation will not load on hardware simulator

[davidtaylor23]

I am not too sure what is stopping my ALU implementation from loading onto the hardware simulator. Here is what I have:
   Mux16(a=x, b=false, sel=zx, out=outzx);
   Not16(in=outzx, out=outnotzx);
   Mux16(a=outzx, b=outnotzx, sel=nx, out=outzxnx);
   Mux16(a=y, b=false, sel=zy, out=outzy);
   Not16(in=outzy, out=outnotzy);
   Mux16(a=outzy, b=outnotzy, sel=ny, out=outzyny);
   And16(a=outzyny, b=outzxnx, out=outyandx);
   Add16(a=outzyny, b=outzxnx, out=outyaddx);
   Mux16(a=outyandx, b=outyaddx, sel=f, out=outf);
   Not16(in=outf, out=outnotf);
   Mux16(a=outf, b=outnotf, sel=no, out=out);
   Mux16(a=outf, b=outnotf, sel=no, out=outno);

   Not16(in=outno, out=notoutno);
   CumAnd16(a=notoutno,out=zr);

   And(a=outno[15], b=outno[15], out=ng);

CumAnd16 is just a chip I made to and together 16 bits and that loads fine onto the simulator. Any help would be greatly appreciated ! :)

[WBahn]

What error are you being given?

[davidtaylor23]

None at all, it won't load onto the simulator. That usually happens if I make a syntax error in the hdl, but I can't seem to spot one here.

[WBahn]

One problem you have is that you are trying to tap off an internal signal (outno[15]). This HDL doesn't support that. You can only tap the chip pins.

So if you wanted to take the least significant bit of the 16-bit output from a Mux you can't do the following:

Mux16(a=x, b=y, sel=x, out=muxout);
Not(in=muxout[0], out=tappedInverted);

You would do it like this:

Mux16(a=x, b=y, sel=x, out=muxout, out[0]=tapped);
Not(in=tapped, out=tappedInverted);

This is described in the Hardware Survival Guide that is linked at the top of the Hardware forum.

[WBahn]

There's usually an error message at the bottom saying why it won't load.

[davidtaylor23]

Thank you very much! It now loads :)