Specifications

■ Make sure you are using an IEEE-1284 parallel printer cable. Many inexpensive cables still sold in stores do not
support IEEE-1284 modes, such as EPP and ECP, and leftover cables you previously used with a dot-matrix or
other printer probably don’t either. Some printers come bundled with an IEEE-1284 cable, but if you must buy
one, expect to pay $10–$30 for one, depending on brand and length. I recommend the 10-foot cable because
it gives you more flexibility than the 6-foot cable for printer placement.
Processing
After the printer receives the data from the PC, it begins the process of interpreting the code. Most
laser printers are really computers in themselves, containing a microprocessor and a memory array
that functions much like the equivalent components in your PC. This part of the printer is often
called the controller or the interpreter and includes the firmware supporting the page description lan-
guages the printer uses.
The first step of the interpretation process is the examination of the incoming data to distinguish the
control commands from the actual content of the document. The printer’s processor reads the code
and evaluates the commands it finds, organizing those that are to be part of the formatting process
and executing others that require physical adjustments to the printer configuration, such as paper
tray selection and simplex (single-sided) or duplex (double-sided) printing. Some printers also convert
the document formatting commands into a specialized code that streamlines the formatting process
to come, whereas others leave these commands in their raw form.
Note
A common error after changing printers is failing to set the new printer as the default printer. This often leads to sending
the wrong printer commands to the new printer, resulting in many sheets of paper covered with gibberish because the
printer doesn’t understand the (incorrect) commands being sent to it. This is also a concern when using a two-printer-to-one-
PC switchbox. You must switch the box to use the correct printer and use the correct printer driver to send the document to
avoid garbage printing.
Formatting
The formatting phase of the data interpretation process involves the interpretation of the commands
that dictate how the content is to be placed on the page. Again, this is a process that can differ
depending on the processing capabilities of the printer. With low-end printers, the PC does much of
the formatting, sending highly specific instructions to the printer that describe the exact placement of
every character on the page. More capable printers perform these formatting tasks themselves, and
you might be surprised to find just how much work your printer does in this respect.
Your application might display your document in a WYSIWYG format that looks very similar to the
printed output, but this is not necessarily how the printer driver sends the document data to the
printer. In most cases, the printer actually lays out the document all over again by interpreting a
series of commands that dictate parameters such as the paper size, the location of the margins, and
the line spacing. The controller then places the text and graphics on the page within these guidelines,
often performing complex procedures, such as text justification within the printer.
The formatting process also includes the processing of outline fonts and vector graphics to convert
them into bitmaps. In response to a command specifying the use of a particular font at a particular
size, for example, the controller accesses the font outline and generates a set of character bitmaps at
the correct size. These bitmaps are stored in a temporary font cache where the controller can access
them as needed while laying out the text on the page.