On Mon, Oct 05, 2020 at 12:56:05AM +0200, Emanuel Berg via Users list for the GNU Emacs text editor wrote:
> Patrick Mahan wrote:
> 
> > Yes, I have never byte-compiled it as I have only
> > used it interactively to clean-up text files coming
> > from a DOS world to linux/unix/macos. It is defined
> > in my .emacs init file.
> 
> Well, you can byte-compile your .emacs as well. It is
> just another Elisp file...
> 
> Anyway, here (last) is a refined version, if you
> don't mind...
> 
> I wonder tho... why does (insert-char 13) insert ^M
> but M-x insert-char 13 RET inserts ^S?

Because the interactive version (your second above) tries to be
helpful and interprets the 13 as hex, whereas the non-interactive
is plain lisp, and there 13 is decimal 13, as it always has been.

To be fair, the interactive version has told you, in the prompt.

But who reads prompts these days? ;-D

(Not intended by any means as a slur at anyone: I've been caught
doing that more than once!)

Cheers
 - t