Up to and including version 7.6, you could choose ASCII as character set for your SAP MaxDB database catalog (8 bit ASCII character set ISO 8859/1.2, which contains 256 characters).
Caution
Starting with version 7.7, the database catalog of all SAP MaxDB databases is stored in Unicode. Before you can upgrade a database with an ASCII database catalog to version 7.7, you first need to migrate the database catalog to Unicode.