TEX uses a coding for the individual characters that is standardized for all implementations, ASCII. This has been fixed for only characters from |0x20| (Space) till |0x7f| (Delete) and some others like || (NUL), | | (CR), | | (LF), || (FF) and | | (Tab) though. (As you see, only 7 bit characters and some control characters.)
In case also for special characters like e.g. umlauts a set for the 8 bit characters (characters ≥128) exists, in any case a translation of the coding of the Amiga will become necessary to the one used in TEX(̇A very awkward sentence to translate, I hope I got it right -TT) Now, you can ``hardcode'' this into the implementation or you leave the user the freedom to be able to determine this in a |Codepage|, so that changes will become quite easy.
The codepage is machine dependant, i.e. if you transfer TEXfiles between
two computers with a different character set, you must also change the
Codepage. Only the coding that is used internally by TEX is the same on
all machines.