Using the Decker/Hirshfield Logic Simulator

While studying Gates and Circuits, we are going to use some software associated with one of the texts on our recommended reading list, The Analytical Engine: An Introduction to Computer Science Using the Internet, by Rick Decker and Stuart Hirshfield.

  • Using the software
    You will need an Internet connection, as the software is available on a webiste maintained by the publisher. The two labs we will be interested in using are:
  • Lab 7.1
  • Lab 7.2
    • Both labs are based on the same software. The only difference is the discussion in the associated prose.

    Once you are viewing the main page for the textbook's software, you will find their labs organized by chapter. You can select the lab you wish to run. For many of the labs, when you run the software for the very first time, a window will pop up labeled with a title such as "Security Warning" and it will ask you whether or not you wish to "trust" the software. Please answer "YES"; we will explain why in the next section.

  • Saving and Loading files
    The software gives you the ability to save your work to a file, and to load those files at a later time. This is a very useful feature, as it allows you to play with the software and save what you did for another time. Also, this will let you save work to a file which can be submitted for the assignment. Also, this allows you to load files which we have created (see next section).

    There is one catch to using the save/load features, because the software will be running from within your web browser. For security reasons, software running in a web browser is not allowed to access files on your computer without explicit permission. This is to help protect against viruses or other malicious attempts to corrupt your computer and its files. The only way such software is given access to saving or loading files is by explicitly getting your permission, as we described in the preceding section.

    So long as you granted permission, in advance, you will be able to save and load files. Generally, the software will include buttons at the bottom right of the program screen labeled "Open" or "Save" or "Save as." If you have been working on a newly created configuration, you must use "Save as" so that you can provide a filename and location to be used. If you are modifying a previously saved configuration, you can choose between "Save" which will overwrite the previous file with the current configuration, or "Save as" which will allow you to give a new filename (while still keeping the previous versioin saved in its prior form).

    If you have mistakenly typed "NO" to the software's original request for your permission, please see the "Trouble shooting" section below.

  • Using files that we provide
    In lecture, there were several files which we used for pre-made circuits. If you wish to play with these files, they are available to you in one of three ways:
  • They can be downloaded and saved to your own computer from the following website.

    However, you cannot simply click on those files when you wish to use them. You must instead start the software as normal, and then you can open the file by using the "Open" button, as described in the preceding section.

  • If you are on the department network, I have placed a copy of the software on the E: drive
  • If you are on the campuswide network but have mounted the departmental network, you will find the copy of the software on the I: drive

  • Trouble shooting
    If you have mistakenlty typed "NO" to the request for full permissions, the program will have a "Save" and "Save as" button, however if you try to use one of them, you will see a window appear saying something to the effect of "Error opening file dialog: (your browser won't allow it)".

    Worse yet, once you respond "NO" your computer may try to remember your answer and so even if you close the window and rerun the program, it no longer asks you about permissions; it thinks it knows of your desire to say "NO".

    If you are unable to save files, try the following two solutions:

    1. Close your browser completely. Then restart the browser and try to view the lab again. If it asks you about granting permissions, answer "YES"

    2. If the software does not ask for your permissions when restarting, and thus you are still unable to save files, this means your browser is remembering your answer from an earlier session. To remedy the situation in Internet Explorer, do the following:
    3. Go to the Tools menu at the top of the browser
    4. Select Internet Options
    5. Click on the Content tab of the new window
    6. Click on the Publishers button at mid-window
    7. You should see an entry for "International Thomson Publishing" - click on this entry and then the Remove button. Then click on OK
    8. Now quit your broswer, restart it and try again. Hopefully it will ask you to grant permissions (and certainly you should say "Yes")

      9. (If you are using Netscape, or an older version of Internet Explorer, contact me for help)

    • Last modified: 31 January 2003