Microsoft GW-BASIC on IBM compatibles allowed flags to the
SAVE command, to indicate the manner in which a file should be written out.
As I recall, it allowed for no flag to write a standard tokenized format,
,A to write a plain-text ASCII BASIC listing, and
,P to write a "protected" file.
"Protected" files looked like gibberish on disk even compared to the tokenized files, and the interpreter would at least refuse to
LIST the source code. As I recall the file size also wasn't the same. They did however run just fine when given to the interpreter.
How were such "protected" files encoded? What about them was different compared to an ordinary tokenized save (no flag)?