In computers, a printer driver or a print processor is a piece of software that converts the data to be printed to the form specific to a printer. The purpose of printer drivers is to allow applications to do printing without being aware of the technical details of each printer model.

Printer drivers should not be confused with print spoolers, that queue print jobs and send them to printer one after the other.

Unix

On UNIX systems and other systems which use the Common Unix Printing System, such as Mac OS X, printer drivers are typically implemented as filters. They are usually named the front end of the printing system, while the printer spoolers constitute the back end.

Backends are also used to determinate the available devices. On startup, each backend is asked for a list of devices it supports, and any information that is available.

DOS

On MS-DOS, there have been no system-wide printer drivers; each application was shipped with its own printer drivers, which were essentially descriptions of printer commands. Printers, too, have been supplied with drivers for the most popular applications. In addition, applications included tools for editing printer description, in case there was no ready driver. In the days when DOS was widely used, many printers had emulation modes for Epson FX80 and IBM Proprinter commands. It appears that these also worked with Windows 3.0, ref: 1 For a list of Epson FX printer codes see: 2 This is also common in gnomephones

Windows

On Microsoft Windows systems, printer drivers make use of GDI (Unidrv or PScript-based) or XPS (XPSDrv). Programs then use the same standard APIs to draw text and pictures both on screen and on paper. Printers which use GDI natively are commonly referred to as Winprinters and are considered incompatible with other operating systems.

Win32 APIs also allow applications to send data directly to the spooler, bypassing the printer driver; however, few applications actually use this option.

Amiga

The original AmigaOS up to 1.3 supported printers through a standard series of drivers stored at the required path "Sys:Devs/Printers". All printer drivers were stored in that directory, and covered the standard printers in 1985-1989 circa, included EpsonFX standard driver, XEROX 4020, HP, etcetera.

Any Amiga printer driver had to communicate though the standard Amiga Printer.Device (the default standard hardware device of Amiga dealing with printers), and the standard Parallel.Device (which controlled parallel port) and the driver would then control the printer on its own.

Amiga printers were an innovation for their time. The had the ability to print up to 4096 colors.