Browse Prior Art Database

Display Subsystem

IP.com Disclosure Number: IPCOM000100392D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Bates, MD: AUTHOR [+5]

Abstract

This article describes a solution to the problem of emulation and display of video from a base display subsystem of a computer system when an additional display subsystem adapter is present in the system for supporting monitors not supported by the base display subsystems.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Display Subsystem

       This article describes a solution to the problem of
emulation and display of video from a base display subsystem of a
computer system when an additional display subsystem adapter is
present in the system for supporting monitors not supported by the
base display subsystems.

      Compatibility Problems The base display subsystem of many
current personal computer system units is the Video Graphics Array
(VGA). From a programming DISPLAY SUBSYSTEM  -  Continued point of
view, it provides numerous display 'modes' as shown in Fig. 1.  These
modes represent higher resolution VGA modes, as well as modes to
provide compatibility with the previous EGA, CGA and MGA adapter
standards.  Higher resolution and more function is desirable to
enhance personal computers, but the hardware cost of compatibility
rises as all the old standards (Fig. 2) must be supported with full
hardware compatibility.

      The Solution The problem of 100% hardware VGA emulation on
non-VGA display monitors is achieved by 'capturing' the video from
the base display subsystem on the personal computer planar, into the
local display memory of an additional display subsystem via an
Auxiliary Video Connector.  Once in that local display memory, this
is displayed on the non-VGA monitor which is attached to the
additional display subsystem.  The CRT controller of the additional
display subsystem is arranged to be completely programmable, so that,
for example, 656 X 496 (in...