Browse Prior Art Database

Enabling/Disabling Video Bus for Industrial Systems

IP.com Disclosure Number: IPCOM000120632D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 101K

Publishing Venue

IBM

Related People

Barber, JN: AUTHOR [+4]

Abstract

Described is a method for enabling/disabling the video bus for industrial personal computer systems so as to minimize electro-magnetic radiation levels caused by simultaneous switching of pixel signals. The method utilizes a software bit-sensing approach to determine the presence of video adapters.

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This is the abbreviated version, containing approximately 52% of the total text.

Enabling/Disabling Video Bus for Industrial Systems

      Described is a method for enabling/disabling the video
bus for industrial personal computer systems so as to minimize
electro-magnetic radiation levels caused by simultaneous switching of
pixel signals.  The method utilizes a software bit-sensing approach
to determine the presence of video adapters.

      Typically, industrial personal systems use analog monitors to
display applications and require video monitors made up of over
200,000 pixels.  The pixels are stored digitally in a byte-wide data
format.  The data is transmitted within the system via a pixel bus in
an eight- bit-wide data path.  Information is converted to analog
red/green/blue (RGB) signals by using a video digital-to-analog
converter (DAC) located on a system resource circuit card.  The RGB
signals are then sent to the video monitor so that the image can be
displayed.  A single video graphics array (VGA) monitor is attached
to one of two video ports on the system resource circuit card.  Fig.
1 shows the standard system resource circuit card bus configuration
and indicates the approximate path of the video pixel bus from the
VGA gate array module connected to the video DAC module and to the
various external connectors. An additional approach (not shown)
enables the pixels to be sent to an optional video adapter for
further processing so as to enhance images and colors.

      To accomplish the desired display flexibility, the video pixel
bus signals must extend across the width of the system resource
circuit card and out to a system backplane so as to propagate the
signals across the system bus.  The system backplane, as shown in
Fig...