HP PCL 5 - Page 199

ENWW Memory Usage 5-3
Additional MEt Features
With MEt, font data can also be compressed. All downloaded bitmap
characters and characters scaled from internal or downloaded
scalable outlines can be compressed. The amount of memory
savings varies with the size of the characters involved (larger is
better) but character sizes can typically be cut in half. This allows
roughly twice as many fonts to be downloaded or scaled using a
MEt-enhanced LaserJet printer as previously allowed on printers
without MEt.
In prior PCL 5 printers, if the page could not be rendered as fast as
the laser printed it, a Print Overrun error occurred unless page
protection was manually turned on and memory was added to
accommodate it. With MEt, the manual setting of Page Protection and
the additional memory required to facilitate it is obsolete. MEt
automatically assesses the complexity of the page being printed and
if too complex turns on a new form of page protection which uses
compression to remove the requirement for additional memory.
In rare circumstances MEt's assessment of the page may prove to be
incorrect. For these cases there is some amount of control over this
Page Protection process depending upon which MEt-equipped printer
is being used. Page Protection may be explicitly turned on or off to
avoid the complexity assessment and either always or never perform
the page protection process. See the appropriate user manual for
details.
MEt also includes other internal memory-saving techniques which
improve the amount of memory required for the printer's internal
representation of your page.
ADC and MEt Notes
For raster graphics compression to perform at its best it is
recommended that the “Recommendations For Sending Data to the
Printer,” described below, be followed.
Character bitmaps can only be compressed if they can be stored
uncompressed in contiguous printer memory first. This requirement
implies that large point size characters may require more printer
memory than would seem necessary.
During MEt's Page Protection, portions of the internal representation
of the page are discarded to make room for other aspects of the page
protection process. If a memory out condition occurs during this