Overview
 About the PRINT interface:
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 The Expand Library since provides support for the DOS PRINT interface.
 To work with any of the function provided in this section one has to
 install the PRINT program. Refer to your DOS manual.

 This interface makes it possible to PRINT files in the background, where
 DOS handles everything for you, so one needn't bother, ans also, one
 knows that it is available for any DOS 3.10+ machine.

 I had to correct some of the PRINT routines, as it seemed some versions
 of DOS behaved slightly differently. The functionality, however, remained
 the same. The correcting done was in the field of Assembly programming,
 some subtle register stuff.