In the printer, a ``formatter'' converts the print data to dot patterns, storing enough dots to make a complete physical cycle, usually a single pass of a print head or a single page. The formatter accepts print data in one or more forms, sometimes called printer languages. Formatters that handle more than one such language may include commands to switch between languages, or they may switch automatically by analyzing the data stream.
Such languages fall into two general categories:
Printer languages such as PCL, HPGL, and ESC-P. These languages use data streams in which the data consists of (1) text bytes, (2) 2-5 byte command strings for horizontal and vertical spacing and line- image (vector) graphics, and (3) strings of bit-image (raster) graphics. This data is easily and quickly converted.
Page description languages (PDLs), such as PostScript (PS) and PCL-V. These languages are actually a subset of the printer languages group, but they use much more complex data streams. Consisting largely of verbose English phrases and programmatic constructions, PDLs allow more complex data manipulations than the simpler printer languages, but require more time to convert.
Choosing the right printers for your network involves more than determining a printer's output speed. PostScript printers can accommodate most inconsistencies that PCL printers cannot, so if possible, make sure your printers are PostScript compatible.