The use of Command-K (under System 6.x), or using the "Postscript File"
destination option in the Print dialog (under System 7) to create a
PostScript file actually adds the information from Laser Prep to the
beginning of the file being generated. This eliminates the need to send the
Laser Prep header separately. In fact, there is a chance that the problem
is being caused because the header is being included.
There is a segment of PostScript included in Laser Prep header that checks
to see if certain routines are already loaded in the LaserWriter RAM. If
they are, everything from that point in the header to the next Control-D
character is deleted from the print job. Unfortunately, when the header is
added to the PostScript file, no Control-D is appended at the end of the
header information. Therefore, the next Control-D reached is the end of the
file, which effectively flushes the job by deleting everything but the
header.
Solution
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1) Using a blank document, generate a PostScript file, which contains the
header, by (under System 6.x) holding down Command-K when you select the
OK button in the Print dialog box, or by (under System 7) clicking the
"Postscript File" radio button in the Print dialog. This generates the
header only. Send this file to the LaserWriter. You must do this once
per power-on cycle of the LaserWriter, unless you need to switch
headers.
2) When you are creating files from documents that you want printed, hold
down Command-F (under System 6.x) when you select the OK button in the
print dialog box. This generates a PostScript file without the Laser
Prep header. Because you already have sent the header, the necessary
dictionary is already loaded, and your files should print properly.
Unfortunately, to generate a PostScript file without the Laser Prep
header in System 7, you need a shareware program like Trimmer, which
gives the option of stripping the header from an existing PostScript
file.