Abstract: A VGA controller has a pass through mode and VRAM mode as motion picture display modes, and one of these display modes can be selected by controlling a switch. In the pass through mode, video data input from a video port interface can be directly output to an NTSC/PAL encoder without the intervention of a VRAM. In this mode, original video data can be displayed on a TV with its original quality. On the other hand, in the VRAM mode, the refresh rate for screen display is matched with the vertical sync frequency of video data, and a high-quality image free from any “tearing” can be obtained.

Abstract: Full-motion video data with a sub-picture and sound is recorded in a DVD-ROM drive. The DVD-ROM drive is connected to an ATAPI interface. Using a data buffer of the ATAPI interface, an MPEG stream is transferred to an MPEG2 decoder on the system board at a variable rate, and video data, audio data, and a sub-picture included in the MPEG stream are decoded by the MPEG2 decoder incorporated in the system. The decoded sub-picture is drawn in a VRAM as in normal VGA graphics. The sub-picture image drawn in the VRAM is synthesized with the video from the MPEG2 decoder by a multimedia display controller and displayed on a screen.

Abstract: Full-motion video data with a sub-picture and sound is recorded in a DVD-ROM drive. The DVD-ROM drive is connected to an ATAPI interface. Using a data buffer of the ATAPI interface, an MPEG stream is transferred to an MPEG2 decoder on the system board at a variable rate, and video data, audio data, and a sub-picture included in the MPEG stream are decoded by the MPEG2 decoder incorporated in the system. The decoded sub-picture is drawn in a VRAM as in normal VGA graphics. The sub-picture image drawn in the VRAM is synthesized with the video from the MPEG2 decoder by a multimedia display controller and displayed on a screen.

Abstract: A portable computer comprising a PCMCIA card connector, a PCMCIA controller, a multimedia display controller, a moving-picture bus, a system bus, and a switching control circuit. The PCMCIA controller controls transfer of data to and from a PC card connected to the PCMCIA card connector. The multimedia display controller can process moving-picture data to display moving pictures. The moving-picture bus connects the PCMCIA controller and the multimedia display controller, for supplying moving-picture data only. The switching control circuit is incorporated in the PCMCIA controller, for connecting the PCMCIA card connector to the moving-picture bus or to the system bus.

Abstract: A portable computer comprising a PCMCIA card connector, a PCMCIA controller, a multimedia display controller, a moving-picture bus, a system bus, and a switching control circuit. The PCMCIA controller controls transfer of data to and from a PC card connected to the PCMCIA card connector. The multimedia display controller can process moving-picture data to display moving pictures. The moving-picture bus connects the PCMCIA controller and the multimedia display controller, for supplying moving-picture data only. The switching control circuit is incorporated in the PCMCIA controller, for connecting the PCMCIA card connector to the moving-picture bus or to the system bus.

Abstract: Full-motion video data with a sub-picture and sound is recorded in a DVD-ROM drive. The DVD-ROM drive is connected to an ATAPI interface. Using a data buffer of the ATAPI interface, an MPEG stream is transferred to an MPEG2 decoder on the system board at a variable rate, and video data, audio data, and a sub-picture included in the MPEG stream are decoded by the MPEG2 decoder incorporated in the system. The decoded sub-picture is drawn in a VRAM as in normal VGA graphics. The sub-picture image drawn in the VRAM is synthesized with the video from the MPEG2 decoder by a multimedia display controller and displayed on a screen.

Abstract: Circuits are provided for determining the use of a flat panel display such as a liquid crystal display or a plasma display based on a plurality of input conditions. A switch circuit is provided for cutting off the supply of display driving power to the flat panel display unit when the display unit is not in use. Gate circuits are provided for locking a LCD driving signal to a non-driven level when the non-use of the LCD is determined. A display controller controlling the display of a CRT display unit includes a display data conversion table and a plurality of D/A converters. A circuit is provided for inhibiting the supplement of clock pulses to a display data conversion table, when a display auto off is enabled. Circuits are provided for cutting off the reference current of the display signal output to the D/A converters.

Abstract: A vertical sync signal and a back porch period following the vertical sync signal are detected by a back porch period detecting circuit. A display period setting circuit sets the effective display period on the basis of the back porch period. A display drive means display-drives the plasma display on the basis of the display period, thereby enabling driving a plasma display at a display timing of a CRT display.

Abstract: A portable computer includes a flat panel display unit, a first graphics subsystem used for displaying data on the flat panel display unit, a connector for connecting an optional second graphics subsystem to the portable computer, and a switch circuit for switching the operation of the first graphics subsystem to that of the second graphics subsystem or vice versa. When the second graphics subsystem is connected to the portable computer, the switch circuit switches the operation of the first graphics subsystem to that of the second graphics subsystem, whereby data from the second graphics subsystem are displayed on the flat panel display unit.

Abstract: According to this invention, a panel controller converts display data having 64 gray scale levels for a color CRT output from an RAMDAC into display data having 57 gray scale levels to perform display driving of a color LCD. The panel display controller has a function of generating 7 intermediate pseudo gray scales between the base frames of R, G, and B signals by a frame rate control method in the color LCD having 8 base gray scale levels of each of the R, G, and B signals to generate (180K colors) display data having 57 gray scale levels and a function of generating 3 intermediate pseudo gray scales between the base gray scales of the signals by a dither method to generate (24K colors) display data having 39 gray scale levels. The selection of the frame rate control or the dither method and the selection of the 512-color, 180-K-color, or 24-K-color display are arbitrarily performed, or these selection operations are automatically performed in accordance with a display mode.

Abstract: An apparatus that saves power consumption by reading out display data from a memory and writing data to a display device such that the read operation is set in a sleep state when a same screen display content continues for a predetermined period of time.

Abstract: In a personal computer system which is equipped with a plasma display unit as a standard I/O device having a horizontal resolution of 640 dots and which can arbitrarily be connected to a CRT display unit having a horizontal resolution of 720 dots, a high-resolution display system includes a display timing data register suitable for the horizontal resolution of the CRT display unit. The display timing data stored in the display timing register is converted into display timing data having a horizontal resolution of 640 dots by a display timing converter. The converted timing data is stored in a clock management register, a clock mode register, and a horizontal panning register in a CRT controller. The high-resolution display system includes a circuit responsive to read access of the respective registers for transferring to a CPU the display timing data which has a horizontal resolution of 720 dots and which is stored in the display timing data register.

Abstract: In a portable personal computer having a flat panel display and driven by battery or by AC adapter, a LOW battery state of battery is detected. In response to the low battery state, a luminance control signal having a minimum luminance value is supplied to the flat panel display. When the personal computer is driven by the AC adapter, a luminance control signal having a maximum luminance value is supplied to the flat panel display.

Abstract: A value obtained by adding a back porch period following a vertical sync signal output from a CRT controller to the total number of horizontal display lines of a display resolution is set in a register. A counter counts the value set in the register in synchronism with a horizontal sync signal, and outputs a scanning start signal to a Y driver. With this operation, when a designated display resolution is lower than the physical resolution of an LCD, the scanning start signal is output before scanning of all the physical display lines of the LCD is completed. As a result, upper and lower non-display portions on the LCD display screen are simultaneously scanned.

Abstract: A display control apparatus in a system which is equipped with a plasma display unit as a standard I/O device and which can arbitrarily be connected to a monochromatic or color CRT display unit, includes a CRT palette in which gradation or color data is set from a CRT-BIOS, a PDP palette in which PDP gradation data is set, an arithmetic circuit for performing a predetermined arithmetic operation of the color data from the CRT palette and outputting gradation parameters, and a conversion table for storing a correspondence between the PDP gradation data and the CRT gradation data or the gradation parameters. The CRT gradation data set in the CRT palette is converted into PDP gradation data by the conversion table for storing the correspondence between the CRT gradation and the PDP gradation. The color data set in the CRT palette is subjected to a predetermined arithmetic operation by the arithmetic unit, thereby generating the gradation parameters.

Abstract: An electronic apparatus having a TFT LCD includes a detector for detecting whether or not display data in a video RAM is rewritten. When the rewrite operation of display data is detected, a display controller reads out display data from the video RAM, and supplies the readout display data to the TFT LCD. When data on a memory plane for storing display data, which is being displayed on the TFT LCD, is rewritten, the display controller reads out display data from the video RAM, and supplies the readout display data to the TFT LCD. When display data to be written in the Video RAM is the same as the already stored display data, the display controller does not supply the display data from the video RAM to the TFT LCD.

Abstract: According to this invention, in a display system having a CRT controller for arbitrarily and selectively display-driving a plasma display and a CRT display, display fonts inherent to the displays are prepared, and a display font corresponding to the display is selectively used and displayed in accordance with a display to be display-driven. The fonts include a plurality of types of graphics and text fonts, and are selectively used. As the text font, a single font and a double font are selectively used. When a display mode of the plasma display having a ratio of the number of dots in the vertical direction to that in the horizontal direction different from that of the CRT display is set, a specific raster of the display screen is scanned twice to stretch an image.

Abstract: A vertical sync signal and a back porch period following the vertical sync signal are detected by a back porch period detecting circuit. A display period setting circuit sets the effective display period on the basis of the back porch period. A display drive means display-drives the plasma display on the basis of the display period, thereby enabling driving a plasma display at a display timing of a CRT display.

Abstract: In a portable personal computer having a flat panel display and driven by battery or by AC adapter, a LOW battery state of battery is detected. In response to the low battery state, a luminance control signal having a minimum luminance value is supplied to the flat panel display. When the personal computer is driven by the AC adapter, a luminance control signal having a maximum luminance value is supplied to the flat panel display.

Abstract: According to this invention, in a display system having a CRT controller for arbitrarily and selectively display-driving a plasma display and a CRT display, display fonts inherent to the displays are prepared, and a display font corresponding to the display is selectively used and displayed in accordance with a display to be display-driven. The fonts include a plurality of types of graphics and text fonts, and are selectively used. As the text font, a single font and a double font are selectively used. When a display mode of the plasma display having a ratio of the number of dots in the vertical direction to that in the horizontal direction different from that of the CRT display is set, a specific raster of the display screen is scanned twice to stretch an image.