I think the difference is opening and closing the device. I'm guessing that doing that tells NTVDM to go ahead and print. Even without the CHR$(12) I've got my doubts whether you'll be able to print just lines at a time. You might get forced into printing whole pages at once.
The "Hello" bit was just an test/example. You should be able to substitute your own strings.
|Response Title||Author and Date|
|yeah||Leon Schrecengost on Jul 18|
|print formatting||LeonSchrecengost on Jul 19|
|Try CHR$(10) Line feed or CHR$(13) + CHR$(10)||on Jul 19|
|Line feed||Leon Schrecengost on Jul 20|