Interoperation
The differences between character representation causes problems during modem communication between Ataris and other computers. Cursor movement commands (and even carriage returns and line feeds) from computers not using ATASCII will be nonsense on an Atari, and vice-versa. Terminal programs need to translate between ATASCII and standard ASCII.
Some Atari-based BBSs exploited this difference by asking the client to hit the "Return" key. If it got 13 (ASCII CR), then standard ASCII would be used. If it got 155 (ATASCII CR) it would switch to ATASCII, allowing full use of the ATASCII graphic set. Some Atari BBSs would also block features (or even block access completely) for non-Atari users.
Read more about this topic: ATASCII