The LaserWriter Select 360 has the ability to sense an interface port
data stream to determine the start and end of PostScript print jobs,
PCL 5 print jobs, PC DOS PrtScn dumps, Hewlett Packard TBCP (Tagged
Binary) and raw text dumps. This function is the key to providing
simultaneously active ports and seamless switching between PCL 5,
PostScript, and raw text printing.
Each interface port has the ability to process either a single
emulation or multiple emulations. If an interface port is assigned
multiple emulation responsibilities, all data sent to it is processed
by the data sensing function. Ports configured for single emulation
responsibility have the data sent directly to the assigned emulation
processor.
Fonts that are downloaded for specific jobs remain in memory for the
PostScript environment and the PCL 5 environment. If the active
environment (either PostScript or PCL 5) runs out of virtual memory,
inactive downloaded fonts are released as needed to regain enough
memory to perform the current job.
The success of automatic emulation switching is tied to the correct
usage of the Hewlett-Packard Printer Job Language, the use of PCL 5
print job delimiters, and proper implementations of the Adobe Document
Structuring Conventions. Job streams that do not abide by the
protocols produce print data that can't be properly sensed and
processed.
Article Change History:
23 Aug 1994 - Review for accuracy.
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