Non-numerical text functions like you'd expect. It will display fine. As I stated, only a number will have problems if you don't include a location. Notice in your last example that the 4 is not shown. A number is part of the command if no location is given before it. If you have nothing after the number, it will give an error because there isn't anything to display. If something is after it, the text will display, but the number will not. It's the color. As I said, read the help file for /echo and it makes sense why it works that way.
And you really need to get rid of the 65 in $asc(). If you want the value from "6", then use $asc(6). Anything following the first character in $asc() is ignored. The result for $asc(6) is the same as for $asc(65) or $asc(60279357823682368972357325) or $asc(6kjasfj32t50jsldkjf345) or whatever else. 65 has no meaning in $asc().