A.X.E.'s handy base converter allows you to see data quickly in any form.
The 'C-Style String' field allows you to see how the bytes you've typed can be represented as a string in a C program (and to type characters such as a linefeed).
The base converter uses the same code that is used to display and edit structures throughout the rest of A.X.E. (In fact, it *is* just an A.X.E. document displayed differently; hey, I can do this 'code reuse' stuff!) and the same notes therefore apply, i.e. that actual interpretation of bytes as characters can depend on your code page (and, it seems, O.S.).
The 'Signed' and 'Motorola' checkboxes affect only the integer types.
The 'Binary' field shows you what you last typed into one of the other fields as binary bits. It is not editable. Perhaps in the next version, it will be :)