Browse Prior Art Database

Implementation of Intelligent Printer Data Streams in Hewlett Packard Command Language/Personal Printer Data Streams Printers

IP.com Disclosure Number: IPCOM000104827D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 112K

Publishing Venue

IBM

Related People

Black, B: AUTHOR [+2]

Abstract

Implementation of Intelligent Printer Data Stream (IPDS*) functionally on Hewlett-Packard Printer Command Language (HP PCL**) and Personal Printer Data Stream (PPDS***) printers does not readily provide a mechanism for IPDS font support (multiple font rotations on a single page). To support IPDS fonts on these devices, special font handling techniques were developed. A high-level overview of these techniques is disclosed here.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Implementation of Intelligent Printer Data Streams in Hewlett Packard Command Language/Personal Printer Data Streams Printers

      Implementation of Intelligent Printer Data Stream (IPDS*)
functionally on Hewlett-Packard Printer Command Language (HP PCL**)
and Personal Printer Data Stream (PPDS***) printers does not readily
provide a mechanism for IPDS font support (multiple font rotations on
a single page).  To support IPDS fonts on these devices, special font
handling techniques were developed.  A high-level overview of these
techniques is disclosed here.

      Print Services Facility/2 (PSF/2*) provides support of IPDS
fonts on PCL and PPDS printers using these specialized font handling
techniques in a special device driver, hereafter referred to as the
PCL/PPDS device driver.  Single-byte IPDS fonts can be printed on a
single page in 16 different combinations (4 character rotations and 4
different print orientations).

      The following issues are addressed with this implementation:

o   Inability to print fonts in multiple rotations on a single page
o   Printer memory storage limitations
o   Centronics interface data transfer limitations
o   Selection of the same IPDS font (type style) in different
    rotations

      Due to PCL and PPDS restrictions, all fonts are sent to the
printer in the 0 degree rotation.  This means the PCL/PPDS device
driver may have to rotate the IPDS fonts in order to produce the
correct PCL/PPDS printer font.  IPDS fonts are stored in an index
structure to permit future use of the font and any necessary related
attributes (e.g., code page, font characteristics, font identifier).
To reduce the amount of printer storage required and the transfer of
font data to the printer, only required print characters are sent to
the printer (a process referred to as "font sieving").  The PCL/PPDS
device driver uses the information regarding the status of fonts
present in its memory and in the printer to control the downloading
and management of fonts.

      To control the processing of IPDS fonts, a mechanism of indexes
or tables is constructed.  Two distinct tables are constructed:

o   Font Index
    This table describes which characters exist as it within the
    font, and in which locations, and where they are presently
    available.
o   Font Control

    This table contains the actual character raster patterns, along
    with dimensions of the font.

      The font control and index tables are built when the PCL/PPDS
device driver receives IPDS Load Font Control and Load Font Index
commands for the specific font.

      These tables are used to record:

o   System and printer identifiers related to the font
o   Which IPDS fonts have been received
o   The characteristics of fonts (dimensions)
o   The available rotation of the font image rasters
o   Whether the font(s) have been downloaded to the printer

      The first time a font is refer...