XPisLpt()
  Indicate whether the printer is On-Line
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   Function:   XPisLpt()

               This function is equivalent to Clipper's ISprinter(),
               except that it works on more ports. Note that the
               function merely returns the Busy status of the Printer,
               so there are quite some situations where XPisLpt()'s
               output can be confusing. This also applies when taking into
               consideration the number of Printer types these days.

   Syntax:     XPisLpt([nLPT])  --> lReady

   Arguments:  nLPT is the Printer port to isialise. Defaults to
               0, which indicates LPT1. 1 indicates LPT2 etc..

   Returns:    lReady indicates whether the printer is ready to
               accept characters.

   Usage:      if !XPisLpt(0)
                   ? "Can't Print"
               end