Browse Prior Art Database

Graphics Adapter Programming Interface with Separable Device Drivers

IP.com Disclosure Number: IPCOM000106683D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 155K

Publishing Venue

IBM

Related People

Cook, JA: AUTHOR [+2]

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.

Graphics Adapter Programming Interface with Separable Device Drivers

      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, which includes
    more than one graphics model for drawing graphics objects

o   a set of graphics adapters and their respective associated CRT
    monitor or other display devices,

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

      In systems such as those described above, the prior art fails
to account for a proper distinction between device-specific
considerations and graphics-model-specific considerations.  For
instance, in prior art, for each graphics model, there was a separate
device driver for each graphics adapter.  Several examples of
problems arose from this previous style of design.

      One such problem arose from the tendency to embed the device
driver code for each graphics adapter into the code of the graphics
models.  For example, the prior versions of the IBM graPHIGS* model
had its own device drivers for the set of IBM graphics adapters,
while the prior versions of the IBM offering of the X Windows System
had its own versions of graphics device drivers.

      The activity of adding support for a new graphics adapter would
create several problems.  First, access to the source code of all of
the graphics models were required, because the device driver for the
new graphics adapter was imbedded into the graphics model.  Second,
the introduction of the new adapter products becomes tightly coupled
to the release schedule of the graphics model, because the hardware
support for the new graphics adapter is imbedded into the graphics
model code.  Third, utilization of shared knowledge of
device-specific programming techniques is poor, because the
specializations of the development teams remained associated with the
graphics model rather than with the graphics device.

      Another such problem is that the programming interfaces to the
graphics device drivers within each of the graphics models did not
use common styles or interfaces.  While variation of device driver
function between graphics models is natural and desirable, variation
inside a single graphics model on a per-device basis substantially
increases the code complexity of the graphics model.

      This disclosure addresses the problems described above, by
creating a programming technique and interface methodology that
enables the separation of hardware considerations and model
considerations.  The technique of the disclosure also enables the
uncoupled release of new adapter support, independent of the release
of the graphics models software which might utilize the graphics
adapter.  Our technique has also proven to help in other ways, suc...