It is based on code page 437, the original character set of the IBM PC.
The following table shows the Atari ST character set.
Using Alt codes, users can enter a character by holding down the Alt key and entering the three-digit decimal code point on the Numpad.
[2] The Atari ST character set long predates the introduction of the euro currency and thus does not provide a code point for the euro sign (U+20AC, €).
However, some software (such as Calamus) utilizes code point 238 (0xEE) for this purpose.