difference between text edit and hex editor?

You can't read or type unprintable byte sequences in TextEdit.

Find some basic reading material on how computers work.
Read up on how a computer displays letters on the screen.
Read up on how a computer displays pictures on the screen.
They use a text window to display text and they use a graphics window to display pictures. The same Hexadecimal numbers will look very different on each type of computer "window".

Go to "How stuff works.com" Look in computers.. etc or any good book store.

Hexadecimal code is a convenient numbering system for computers to use.
It's a mathematical numbering system using a base of 16 rather than 10 which we usually use. ie; 0123456789 (10 numbers) as opposed to 0123456789ABCDEF (16 numbers used in Hexadecimal).

There's much to learn, get started !!

TTab

Any file is made up of a sequence of bytes. Each byte is a sequence of 8 bits. Each bit is either 1 or 0. Therefore, each byte can have a value between 0 and 255. Using ASCII encoding, each byte value represents a particular character, such as 'A', 'B', 't', '#', etc. In the entire range of 256 ASCII characters, only a subset are considered to be "printable". If there is a file made up of only those printable characters, that file is considered to be "text". If there is a single character outside of the "printable" range, the file is considered to be binary.

A "text" file is sometimes treated specially and can have its line ending character \n, \r, or both, changed or switched around depending on the operating system. It is a long story.

A hex editor will display all of the printable characters in a file and represent the non-printable characters with just a '.' or space. It will also display the hexadecimal value of each character, printable and non-printable. It may also be able to group bytes together and extract some higher-level meaning out of them.

http://en.wikipedia.org/wiki/Hex_editor

Just FYI, if you decide to play with a hexeditor, make a copy of the file you plan on editing first.

http://www.apple.com/downloads/macosx/development_tools/0xed.html

Message was edited by: Nils C. Anderson