Abstract: A data input apparatus having a keyboard with a plurality of character keys and a memory for storing first, second and third control tables. The first control table contains a first key arrangement with an internal code train that is input by depressing a corresponding key on the keyboard, the second control table contains a second key arrangement with a logic structure different from the first control table and stored in a rewritable memory, and the third control table identifies which of the keys of the keyboard in the second key arrangement are assigned to corresponding to the internal code train input by depressing a corresponding key. Data in the second control table corresponding to the internal code train in the third control table can be edited and one of the first and second control tables in the memory can be selected for performing key input data conversion.