HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part I
EN Free Space Command 16-21
Free Space Command
The Free Space command returns the amount of available memory.
This response returns two values: the total available memory, and
the largest available block of memory (refer to the “Memory Status
Response” section later in this chapter for additional information).
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If a value other than 1 is sent, this command returns an error
(“ERROR = INVALID UNIT,” refer to “Memory Error Response”
section later in this chapter for additional information).
To identify whether the printer has enough memory available for a
job, you can send the Free Space command to compare the space
available with that needed. You can also identify how much memory
an entity or any other data uses by checking the amount of free
memory prior to downloading the data, then downloading the data,
and checking memory again. The difference in these values
represents the approximate memory needed.
Note Many conditions can cause the available memory to change or
appear different. Some of these conditions are listed below.
The actual printer memory required to store an item varies slightly
based on printer memory fragmentation and other internal printer
conditions.
Different printer models use different methods to store data. Thus, the
amount of memory required to store the same amount of data may be
slightly different in different printers.
While the printer is processing page data, the available memory is
constantly changing due to the printer receiving new data, processing
existing data, and adding new characters to the font cache, etc. Under
these conditions, the available memory may change by the time the
memory response is returned.
If a PostScript SIMM is installed in the printer, some memory is not
reported for a Free Space command response. This memory is not
reported as part of the free memory for a PCL status readback
response, however, this memory is available for PCL use. Thus, it is
possible for all or part of the downloaded data to be stored in this
section of unreported memory and not change the memory response
size.