HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part I

16-22 Status Readback EN
If you determine there is insufficient memory to hold the data to be
downloaded, some action is required. One method to make more
memory available is to send the Flush All Pages command. This
causes the printer to clear (process) the current page data from
memory without accepting any new data for processing (refer to the
“Flush All Pages Command” described later in this section). Another,
more comprehensive method to clear memory is to send the Printer
Reset (
E
C
E) command. This not only removes data (deletes all
temporary entities and the font cache) but also restores the User
Default Environment settings (refer to the Printer Reset command
in Chapter 4, “Job Control Commands”).
Note To print characters from a scalable font, the printer converts the
scalable character outlines into sized bitmaps. These bitmapped
characters are created on a character-by-character basis as they
are needed for printing and are stored in memory. As more pages
are printed using more fonts, the bitmaps consume more memory.
The bitmap characters used on the first page of a job can remain in
memory until the end of a job. These stored bitmap characters are
referred to as the font cache.
Note When an HP LaserJet 4 printer (or later) reaches a memory low
condition it automatically deletes all of the font cache. It is possible
to delete the cache immediately using a Printer Reset command.
A Printer Reset clears the font cache, clears temporary entities,
and restores the user default environment.
Memory Status Response
A Free Space status response returns two values:
TOTAL=
LARGEST=
“TOTAL=” identifies the total available user memory (in bytes). This
value includes the largest block available and all smaller blocks.
Note Data downloaded to the printer is stored in a block (continuous
section of free memory). If the printer does not have a large enough
block to store the data, then the data is discarded and a memory
error results.