You can connect a Laserwriter to the RS232 backplane of a VAX and send VAX
PostScript files to the printer as long as the files sent are written,
saved, and sent as full PostScript files.
To be considered a full PostScript file, the LaserPrep header MUST be
present in the PostScript text file. If, for instance, you create a
PostScript text file on a Macintosh, and store the file on a VAX to print
later, the Laser Prep header must also be included when you actually print
that file.
Under System 7, choosing "PostScript File" in the Destination option of the
Print dialog box automatically includes the LaserPrep header (in fact, the
only way to exclude the header under System 7 is by using the shareware
utility Trimmer, which can strip off the header).
Under System 6, the same result is achieved by holding down Command-K
immediately after clicking Okay in the Print dialog box.