Browse Prior Art Database

Method of Direct Access to Display Windows

IP.com Disclosure Number: IPCOM000106717D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 160K

Publishing Venue

IBM

Related People

Baker, D: AUTHOR [+3]

Abstract

This disclosure relates to computer systems in which the following components are present:

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 34% of the total text.

Method of Direct Access to Display Windows

      This disclosure relates to computer systems in which the
following components are present:

o   an operating system, including input devices

o   a graphics display system, or a windowing system,

o   a graphics adapter and its associated CRT monitor or other
    display device

o   applications programs, which seek to display information on the
    monitor via programmed control of the operating system and
    graphics display system.

      In the system described above, the prior art utilized a single
display system or windowing system to provide access to the hardware
facilities of the graphics adapter.  For instance, on IBM products
the X Windows System software of the AIXwindows* product provides
this function.  The window system, in coordination with the device
driver provided by the operating system, controlled all access to the
hardware of the graphics adapter.  The application programs did not
touch the hardware:  instead, they programmed to the abstraction of
the hardware provided by the display subsystem.

      One problem which results from this approach is that additions
in the function and features of the graphics adapter are never
directly reflected to the application program.  There are several
manifestations of this problem:

o   The application program cannot directly control features of the
    hardware that are not presented via some programming interface or
    logical abstraction of the graphics display system.
o   Each time a change in function to the graphics adapters is made,
    a corresponding change in the application programming interface
    of the graphics display system is required, to expose the change
    to the application program.
o   Existing, de-facto standard display subsystems, such as the X
    Window System, are completely lacking any paradigm to expose
    certain types of hardware function, such as advanced 3-D
    hardware functions.

          Another problem which results from this approach is that
    any applications program which desires to generate graphics is
    restricted to the graphics paradigms and application programming
    interfaces of the graphics display subsystem.  This problem, too,
    manifests itself in more than one way:

o   The application program cannot manage the hardware more directly
    than via the methods exposed by the display subsystem.  For
    instance, if fast I/O services exist in the device driver or
    operating system, but the display subsystem does not provide a
    method to pass I/O requests quickly, then performance will be
    limited.

o   The application program cannot utilize features found in a subset
    of the supported graphics adapters but which are not supported in
    the display subsystem itself.  For instance, if some of the
    graphics adapters support 3-dimensional hidden surface...