HexEdit

1. Download HexEdit from this web-site
   ftp://ftp.sunet.se/pub/simtelnet/win95/editor/hexfre20.zip
    
2. Use a simple Java editor (not NetBeans) to make a very simple Java program that adds two numbers and prints out the answer:
   
   public class Test
   {   public static void main(String[] args)
        {
              int  A = 25;
              int  B = 74;
              int  C = A + B;
              System.out.println("Sum = " + C);
         }
   }
   Save it in the root directory of the D: drive.
   Compile the program, run it, make sure it is working correctly.
    
3. Run Command.com to get a DOS window.
   
4. Run your compiled java class by typing :  java d:\Test.
   It should print Sum = 99.
5. Now run HexEdit and open D:\Test.class
6. Search for the byte containing 25.  Change it to 26.   
7. Go back to the DOS window and run your program again (java d:\Test).
   It should print 100 for the answer instead of 99.
8. Go back to HexEdit and change some other byte.  
   Try running the program again - it will probably cause an error.

Changing Web Pages

1. Surf to Google's main page, and save this on drive D: as Google.html
2. Open the SAVED page in Internet Explorer.  What happens?
3. Find some page on the web that you can save onto D: and then open correctly.
4. Choose some text on the page and change it.  Use any program that might work.
   Open the page and check that it worked correctly.
5. Find one byte (character) in your page that you can change that makes the page NOT load correctly.
6. Find a web-page that contains JavaScript code.  Find something in the JavaScript code that you understand and try to change it.