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Browse Prior Art Database

SVGA Suspend/Resume with External Multi Sync CRT

IP.com Disclosure Number: IPCOM000112759D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 87K

Publishing Venue

IBM

Related People

Nagasawa, T: AUTHOR

Abstract

Disclosed is a mechanism for controlling sync signal of multi sync high resolution CRT attached to the external video port of power consumption manageable personal computer whose primary display device is built-in LCD.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 42% of the total text.

SVGA Suspend/Resume with External Multi Sync CRT

      Disclosed is a mechanism for controlling sync signal of multi
sync high resolution CRT attached to the external video port of power
consumption manageable personal computer whose primary display device
is built-in LCD.

      For example, when external CRT is detached during
suspend/hibernation, display device will automatically switch to
built-in LCD.  For another example, when external CRT is attached
during suspend/hibernation, display device will automatically switch
to externally attached CRT at resume time.  On both cases, sync
signal must be adjusted to newly switched display device.

      At installation time, user specific external display device is
selected from predefined 'display device vs sync signal table' as
shown in table 1.  Selected information is saved to permanent file,
non-volatile memory or battery back up CMOS memory.

                         VGA     SVGA    SVGA    SVGA
                            640x480 640x480 800x600 1024x768
          display device    16color 256clr  256clr  256clr
          ---------------   ------- ------- ------- --------
          TFT LCD 640x480   60Hz    60Hz    n/a     n/a
          TFT LCD 800x600   60Hz    60Hz    70Hz    n/a
          STN LCD 640x480   88Hz    88Hz    n/a     n/a
          VGA CRT 1         60Hz    60Hz    n/a     n/a
          VGA CRT 2         75Hz    75Hz    n/a     n/a
          SVGA CRT 1        60Hz    72Hz    72Hz    n/a
 select-> SVGA CRT 2        60Hz    60Hz    72Hz    60Hz
          SVGA CRT 3        72Hz    72Hz    72Hz    60Hz
          SVGA CRT 4        60Hz    60Hz    72Hz    72Hz
            :   :  :         :       :       :       :

       Table 1.  Example of display device vs sync signal table.

      At suspend/hibernation time, current status of video control
hardware is saved to the device context save area.  At this time,
display device information selected by user at installation is also
saved to the device context save area.

      At resume or hibernation wake up time, sync signal frequency
can be determined by either of the following three cases,

      (case-1) attached external-CRT is still connected after
         suspend/hibernation.

      1.1 The screen resolution used in previous suspend/hibernation
can be obtained by inspecting CRT Controller register which was
restored from device context save area.
1.2 Sync signal frequency can be determined by the resolution
obtained by step 1.1 and display device saved as one of the device
context information as shown in Table 2.

                    ...