Compaq Computer Corporation, Inc.

Abdel H Suboh

Patrick A Harkin

Stuart Hecht

A video controller has one or more shared pins coupled to respective configuration signals. The shared pins are also coupled to other devices external to the video controller. Responsive to a reset signal, the configuration signals are stored in a configuration register. At other times, the external devices can overcome the configuration signals such that the shared pins may be used for other operations of the video subsystem.

Video controller with shared configuration pins

Power is conserved in a video subsystem by inactivating a pixel clock (PCLK) and reducing frequency of a memory clock (MCLK) responsive to an indication of user inactivity. The inactivation of PCLK reduces the power consumed in the RAMDAC, frame buffer, phase lock loop (PLL) clock circuit, and to a smaller extent, the video controller. Reducing the frequency of MCLK conserves power in the video controller and the PLL, while maintaining the integrity of the data in the frame buffer. Significant power savings can be accomplished with minimal BIOS or video controller programming and minimal transfer of state information prior to power-down.

Video subsystem power management apparatus and method

Power is conserved in a video subsystem by inactivating a pixel clock (PCLK) and reducing frequency of a memory clock (MCLK) responsive to an indication of user inactivity. The inactivation of PCLK reduces the power consumed in the RAMDAC, frame buffer, phase lock loop (PLL) clock circuit, and to a smaller extent, the video controller. Reducing the frequency of MCLK conserves power in the video controller and the PLL, In order to maintain the integrity of the data in the frame buffer, the refresh rate programmed by the video controller is increased to offset the reduction of the MCLK frequency. Significant power savings can be accomplished with minimal BIOS or video controller programming and minimal transfer of state information prior to power-down.

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Houston, TX, United States of America

Abdel H Suboh