Eval button keeps being disabled

[yusufgandhi]

Hi there,

In the Hardware Simulator Tutorial PDF file, on page 13 (out of 49), in the section Interactive Chip Testing, we are told to be able to change the value of the input pins.

And when we change the values, the simulator SHOULD respond by:
1) Darkening the output and internal pins,
2) Enabling the eval (calculator-shaped) button.

These two things didn't happen in my Hardware Simulator program. What happened? I included a screen shot from the Hardware Simulator in my computer.



I had edited the Xor.hdl according to the screenshot provided in the tutorial.

Just FYI, I am using Windows XP SP3 on my computer.

Thanks in advance for your support!

[cadet1620]

yusufgandhi wrote

In the Hardware Simulator Tutorial PDF file, on page 13 (out of 49), in the section Interactive Chip Testing, we are told to be able to change the value of the input pins.

And when we change the values, the simulator SHOULD respond by:
1) Darkening the output and internal pins,
2) Enabling the eval (calculator-shaped) button.

These two things didn't happen in my Hardware Simulator program. What happened? I included a screen shot from the Hardware Simulator in my computer.

It looks like the instructions in the Hardware Simulator Tutorial are incorrect.

Copy your Xor.hdl into the projects\00 directory and open that copy in the simulator and you should be able to edit and evaluate as described. Make sure that when you click on "PARTS:" all the chips displayed have type BuiltIn.

What's happening is that when you load your Xor.hdl from projects\01 it is trying to use the Not, And and Or parts in the projects\01 directory. Since you haven't done project 1 yet, these parts have no implementation and the Hardware Simulator is silently failing. Note that in your screenshot (and the one in the tutorial) the chip types are Composite.

When you start on project 1, it is very important that you implement and test the chips in the order listed in 1.3 to prevent this sort of problem.

--Mark

[yusufgandhi]

Thank you for your prompt reply! And it solved the problem!

Please be patient if I have further questions regarding this NAND2TETRIS program :)

On Mon, Oct 8, 2012 at 11:03 PM, cadet1620 [via Nand2Tetris Questions and Answers Forum] <[hidden email]> wrote:

It looks like the instructions in the Hardware Simulator Tutorial are incorrect.

Copy your Xor.hdl into the projects\00 directory and open that copy in the simulator and you should be able to edit and evaluate as described. Make sure that when you click on "PARTS:" all the chips displayed have type BuiltIn.

What's happening is that when you load your Xor.hdl from projects\01 it is trying to use the Not, And and Or parts in the projects\01 directory. Since you haven't done project 1 yet, these parts have no implementation and the Hardware Simulator is silently failing. Note that in your screenshot (and the one in the tutorial) the chip types are Composite.

When you start on project 1, it is very important that you implement and test the chips in the order listed in 1.3 to prevent this sort of problem.

--Mark

---

If you reply to this email, your message will be added to the discussion below:

http://nand2tetris-questions-and-answers-forum.32033.n3.nabble.com/Eval-button-keeps-being-disabled-tp4025192p4025194.html

To unsubscribe from Eval button keeps being disabled, click here.
NAML

--

"GOD will always provide your needs"

[jos van kesteren]

Hi,

Could this behaviour actually be a feature in order to gently force the students to implement the basic blocks first :-)

Jos

[Albert G]

There are two other points I noticed about this:

1) Right after loading a chip, the EVAL button is always disabled. The chip actually runs on the default input for all pins, i.e. all zeros. The EVAL button only gets enabled if you change any of the inputs to a different value.

2) If the chip produces no output at all, then also the EVAL button is disabled. A chip without output ? That makes no sense, will you say. I was actually building up the ALU and wanted to do debugging on the partially built chip. But I noticed I was unable to test anything since the EVAL button never got activated. So I just added a default output to one of the output pins and I was able to do my debugging.

Albert