No Support for Print Performance Architecture under Windows NT

Hewlett-Packard has introduced a new architecture targeted for the home market called Print Performance Architecture (PPA). Conceptually, PPA resembles other high-performance architectures such as Microsoft Windows Printing System and Adobe Print Gear. These technologies offer high-speed output by eliminating any intermediate print language and process pages in the host format (in this case, graphical device interface, or GDI) directly into bitmaps for printing.

Because PPA is a departure from traditional printing architecture, Windows NT is not able to support this device by means of its universal PCL driver (RASDD).

Windows 2000 does support PPA devices.

PPA eliminates any intermediary page description protocol, namely printer command language (PCL), between the host and the printer. As a result, two process-intensive steps are eliminated:

• The conversion of the page description from the graphic environment's form (GDI for the Windows Environment) into PCL by the printer driver is eliminated.
• In the printer, the conversion of the PCL description into a bitmap is eliminated. Instead, in the PPA architecture there is only one conversion from GDI straight to a bitmap.

To better understand the PPA architecture, it is necessary to review how a PCL and PPA device prints.

PCL Printing Process

(Using a Deskjet device as an example)

Host:

• Application and OS System: User chooses to print. Application spools high-level GDI description of printed page to hard drive.
• Rasterization and Bitmap Processing: Windows driver renders GDI objects and translates into four-plane color rasters and text.
• PCL Encoding: Windows driver translates rasters and text into PCL.
• I/O: Windows driver sends PCL to the Printer over the I/O channel.

Printer:

• I/O: PCL data arrives in I/O buffer.
• PCL Decoding and Formatting: PCL data moved from I/O buffer into a format buffer. Text converted to rasters.
• Swath Management: Formatted raster data is moved into a temporary buffer.
• Swath Management: Rasters are converted into Printer sweeps formatted for Print Cartridges.
• Mechanical and Print Head Control: Print sweeps are sent out to the print head and ink is fired, resulting in a printed page.

PPA Printing Process

Host:

• Application and OS System: User chooses to print. Application spools high-level GDI description of printed page to hard drive.
• Rasterization and Bitmap Processing: Windows driver renders GDI objects and translates it into four-plane color rasters and text.
• Swath Management: Rasters are converted into Print sweeps formatted for the Print cartridge.
• I/O: Windows Driver sends Demand Protocol Architecture (DPA) commands to the printer over the I/O channel.

Printer:

• I/O: DPA data arrives in I/O buffer using Direct Memory Access (DMA).
• Mechanical and Print Head Control: Print sweeps are sent out to the print head and ink is fired using DMA.

HP Print Devices That Support Only PPA

Currently, there are three models that support PPA only:

Hewlett-Packard Deskjet 820Cxi (Windows PPA)
Hewlett-Packard Deskjet 820Cse (Windows PPA)
Hewlett-Packard Deskjet 1000c (Windows PPA)

Other HP PPA Printers

Hewlett-Packard Deskjet 720C
Hewlett-Packard Deskjet 722c

These printers support both PPA and PCL3 emulation.

NOTE: Hewlett-Packard no longer supports the DeskJet 720, 722 and 722c series printers under Windows NT version 3.51.