Installing PIT from the Internet

NOTICE: PIT currently does not download from the Internet. Efforts are being made to correct this - watch the HomePage for a statement that PIT is now downloadable from the Website. Those using a CD-ROM should just skip this page for now.

Installation of PIT requires you to modify your AUTOEXEC file so that your computer knows where to find Tcl. The AUTOEXEC file is one of two files that make your computer run properly, so it is possible to seriously adversely affect the operation of your computer while modifying this file. If you follow the steps outlined below and make only the changes listed, there should not be a problem. If you are uncomfortable making these changes yourself then it is recommended that you have someone experienced in this type of work do it for you. Any problems that arise due to modification of this file are the responsibility of only one person - you, or the person who makes the changes if that is not you.

Note: After this Appendix was prepared, feedback from Internet users who tried to install PIT indicated that some were experiencing problems. We insert here a suggestion from Berit Bland, Director of the NASA Visitors Center at Wallops Island, VA. In his own words:

I got the PIT to run by doing the following:

Copy the files tk80.dll, tcl80.dll, and tclpip80.dll into the windows\system directory (where all the other dll files reside). PIT runs fine after this modification. (OS: windows 98) The PATH statement should probably read c:\program files\tcl\bin (backslashes for directories instead of forward slashes). I'm not certain that adding the PATH statement does any good, but it doesn't seem to do any harm either.

You will need a way to unzip the files listed below. If you know your way around DOS you can use PKUNZIP that comes with Windows 95 and WinNT. If you don't then you will need to get a Windows program that does the same thing. A good one to use is WinZip, which you can get from their website.

There are several files that you will need to download -

this zipped file contains all of the files required to run PIT except for those listed below; tcl804.exe is packaged with this file and will install Tcl/Tk 8.0* on your computer, which is necessary for the proper operation of the PIT interface

* Tcl/Tk can also be downloaded directly from the Scriptics website -
these are image files to be used during the walkthrough of PIT later on in this Appendix

Once you have downloaded these files you will need to follow these instructions -

  1. Create a new folder called PIT on your hard drive.
  2. Create a new folder called PIT Images on your hard drive at the same level as PIT.
  3. Unzip into the PIT folder.
  4. Double-click on tcl804.exe to install Tcl/Tk 8.0.*
  5. Add the following to your system PATH (**) - c:/program files/tcl/bin
  6. Unzip the image files into the PIT Images folder.
  7. To execute PIT, double click on the file named "pit.bat" in your PIT folder. Depending on the file manager you use, the ".bat" extension may not be shown and the file type may be listed as an MS-DOS file.
  8. For convenience, you will likely wish to tie the execution file to a screen icon.

* You will first be asked to enter a location for the distribution. The default should be fine but you may specify a different location if you choose. It is recommended that you not specify your PIT folder (or a folder within your PIT folder) which may complicate future updates to your PIT distribution. The Tcl/Tk 8.0 installation process may ask additional questions depending on how your system is configured. If you already have Tcl/Tk 8.0 (or after installing it), the file "tcl804.exe" can be deleted.

** This is to make it possible for PIT to find Tcl when you start the program. If you do not set this correctly then when you try to start PIT it will give you an error stating that the file "tcl80.dll" can not be found in the PATH. On WinNT, to set your PATH follow these steps:

  1. Right click on the "My Computer" icon and then Properties
  2. Click on the Environment tab
  3. Under "User Variables" click on the PATH line
  4. In the Value field near the bottom of the window add the following at the end of the line - ;c:/program files/tcl/bin - make sure you separate the last entry from your new entry with a semi-colon (no spaces)
  5. Click "Set"
  6. Click "Apply"
  7. Click "OK"
  8. Run PIT

On Windows 95 follow these steps:

  1. Double-click on "My Computer" and then double-click on your system drive (should by C:\ unless you have changed it)
  2. Right-click on the "Autoexec" icon and then Edit
  3. At the end of the PATH line add the following - ;c:/program files/tcl/bin - make sure you separate the last entry from your new entry with a semi-colon (no spaces)
  4. Save the "Autoexec" file
  5. Restart your computer so your new settings will take effect
  6. Run PIT


Nicholas M. Short, Sr. email:
Jeff Love, PIT Developer (

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