Laser printers only need enough memory to hold one full page of output at a
time and they MUST have enough memory to hold the entire page before any
image is created.  Otherwise you get only a partial page printed (in PCL
anyway).

Memory can also be used to temporarily store downloaded soft fonts and macros
but the memory requirements for these are usually measureable in 'kb' not
'mb'.  For a laser printer, you can determine the maximum memory you would
normally use for a single page via this formula:

megabytes =
dpi_resolution_horizontal  *  dpi_resolution_vertical  *  page_width  *
page_height /
8000000

For example: a 600 x 600 dots per inch (dpi) printer printing at it's max
resolution for a full page of graphics onto a 11" x 17" size sheet of paper:

600 * 600 * 11 * 17 / 8000000 = 8.415 mb

8mb is nothing today.  This is all a very simplified method of determining
overall memory requirements and this is essentially a 'worst case' scenario.
Postscript might find some ways to eat up more memory than PCL but no matter
what, you don't need more than one bit for each dot to be printed.

What the memory in a LaserJet can also do is act as a buffer so that more
stuff can be queued up inside the printer.  Different models have different
configuration rules and options.  I suspect that it is possible to
over-allocate memory to buffer use instead of page formatting use.  That
might cause what appears to be a memory-overrun problem.

Wayne Boyer
Cal-Logic

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