GDI Laser Technology

The alternative to laser printers which use languages such as PostScript and PCL are Windows GDI (Graphical Device Interface) bitmap printers. These use the PC to render pages before sending them as a bitmap for direct printing, using the printer just as a print engine. Consequently, there’s no need for expensive processors or large amounts of on-board RAM, making the printer cheaper. However, sending the complete page in compressed bitmap form takes time, reducing printing speed and increasing the time taken to regain control of the PC. GDI printers are, therefore, generally confined to the personal printer market.

Some manufacturers elect to use the Windows Print System, a standard developed by Microsoft to create a universal architecture for GDI printers. The Windows Printing System works slightly differently to the pure GDI model. It enables the Windows GDI language to be converted to a bitmap while printing; the basic idea being to reduce the heavy dependence of the printer on the PC’s processor. Under this system, the image is actually being rendered during the printing process which greatly reduces the amount of processing power required from the PC. Other laser printer models use a combination of GDI technology and traditional architecture, allowing fast printing from Windows as well as support for native DOS applications.