Digital/analog conversion apparatus having color palette RAM for multimedia

A digital/analog conversion apparatus with a color palette RAM for a multimedia, comprising first latch means for inputting a pixel address signal from a display control circuit, microprocessor interface means for transferring digital color information from an external microprocessor to said color palette RAM and vice versa and transferring address and control signals from said microprocessor, a pixel mask register for selectively masking the pixel address signal from said first latch means in response to the control signal from said microprocessor interface means, said color palette RAM for storing the digital color information from said microprocessor interface means in its location corresponding to the address signal from said microprocessor interface means and outputting the digital color information stored in its location corresponding to the pixel address signal from said pixel mask register, second latch means for storing the digital color information from said color palette RAM or different digital color information temporarily, and first to third digital/analog conversion means for converting the digital color information from said second latch means into analog R, G and B color information, wherein the improvement comprises:

• first switching means for inputting the digital color information from said color palette RAM at its one input terminal and digital video color information which is directly applied from an external video medium through an independent input terminal of the apparatus at its other input terminal, selecting one of the inputted information in response to an external first control signal and outputting the selected information to said second latch means;
• a color information input line for applying external digital color information directly to said first latch means;
• and
• second switching means for inputting the digital color information from said color palette RAM at its one input terminal and the external digital color information from said first latch means at its other input terminal, selecting one of the inputted information in response to an external second control signal and outputting the selected information to the input terminal of said first switching means inputting the digital color information from said color palette RAM.

A digital/analog conversion apparatus with a color palette RAM for a multimedia, comprising first latch means for inputting a pixel address signal from a display control circuit, a pixel mask register for selectively masking the pixel address signal from said first latch means in response to the control signal from said microprocessor interface means, said color palette RAM for storing the digital color information from said microprocessor interface means in its location corresponding to the address signal from said microprocessor interface means and outputting the digital color information stored in its location corresponding to the pixel address signal from said pixel mask register, second latch means for storing the digital color information from said color palette RAM or different digital color information temporarily, and first to third digital/analog conversion means for converting the digital color information from said second latch means into analog R, G and B color information, wherein the improvement comprises:

• first switching means for inputting the digital color information from said color palette RAM at its one input terminal and digital video color information which is directly applied from an external video medium through an independent input terminal of the apparatus at its other input terminal, selecting one of the inputted information in response to an external first control signal and outputting the selected information to said second latch means;
• second switching means for inputting the digital color information from said color palette RAM at its one input terminal and the output digital color information from said first switching means at its other input terminal, selecting one of the inputted information in response to an external second control signal and outputting the selected information.

A digital/analog conversion apparatus with a color palette RAM for a multimedia, comprising first latch means for inputting a pixel address signal from a display control circuit, a pixel mask register for selectively masking the pixel address signal from said first latch means in response to the control signal from said microprocessor interface means, said color palette RAM for storing the digital color information from said microprocessor interface means in its location corresponding to the address signal from said microprocessor interface means and outputting the digital color information stored in its location corresponding to the pixel address signal from said pixel mask register, second latch means for storing the digital color information from said color palette RAM or different digital color information temporarily, and first to third digital/analog conversion means for converting the digital color information from said second latch means into analog R, G and B color information, wherein the improvement comprises:

• first switching means for inputting the digital color information from said color palette RAM at its one input terminal and digital video color information which is directly applied from an external video medium through an independent input terminal of the apparatus at its other input terminal, selecting one of the inputted information in response to an external first control signal and outputting the selected information to said second latch means
• a color information input line for applying external digital color information directly to said first latch means and
• second switching means for inputting the digital color information from said color palette RAM at its one input terminal and the external digital color information from said first latch means at its other input terminal, selecting one of the inputted information in response to an external second control signal and outputting the selected information to the input terminal of said first switching means inputting the digital color information from said color palette RAM.