Easily upgradeable video memory system and method

A video memory system, comprising:

• video memory module means for storing data representing a video image, including means for generating a selection signal denoting whether said module is a monochrome memory module or a color memory module;
• pixel clock means for generating a pixel clock signal at a predefined pixel clock rate;
• load clock means coupled to said pixel clock means and said video memory means for generating a load clock signal at a first predefined rate when said selection signal denotes that said module is a monochrome memory module, and for generating a load clock signal at a second predefined rate when said selection signal denotes that said module is a color memory module;
• said second predefined rate being an integer multiple of said first predefined rate;
• shift register means coupled to said video memory module means and said load clock means for receiving and storing data from said video memory module means in response to said load clock signal, and coupled to said pixel clock means for outputting in parallel a plurality of bits of said data at said pixel clock rate;
• whereby said selection signal in said video memory module determines the mode of operation of said video memory system and the rate at which data is loaded from said video memory means into said shift register means.

A video memory system, comprising:

• memory module means for storing video data, including means for generating a selection signal having a first predefined value when said module is a monochrome memory module and a second predefined value when said module is a color memory module;
• pixel clock means for generating a pixel clock signal at a predefined pixel clock rate;
• load clock means coupled to said pixel clock means and said memory module means for generating a load clock signal at a first predefined rate when said selection signal denotes that said module is a monochrome memory module, and for generating a load clock signal at a second predefined rate when said selection signal denotes that said module is a color memory module;
• shift register means coupled to said video memory module means and said load clock means for receiving and storing data from said video memory module means in response to said load clock signal, and coupled to said pixel clock means for outputting in parallel a plurality of bits of said data at said pixel clock rate;
• whereby said selection signal in said video memory module determines the rate at which data is loaded from said video memory means into said shift register means.

A method of operating a video memory system having a memory module and data stored therein representing a video image as an array of pixels, the steps of the method comprising:

• generating a selection signal denoting whether the memory module is a monochrome memory module or a color memory module;
• generating a clock signal at a predefined clock rate;
• and
• reading a portion of the data stored in the memory module and outputting data for one pixel of said stored video image during each cycle of said clock signal;
• said reading step reading the data stored in the memory module at a first predefined rate when said selection signal denotes that said video image is a monochrome image, and reading said stored data at a second predefined rate when said selection signal denotes that said module is a color memory module;
• whereby said selection signal determines the mode of operation of said video memory system and the rate at which data is read from said memory module.

A method of operating a video memory system having a memory module and data stored therein representing a video image as an array of pixels, the steps of the method comprising:

• generating a selection signal denoting whether the video image stored in the memory module is a monochrome image or a color image;
• generating a clock signal at a predefined clock rate;
• and
• reading a portion of the data stored in the memory module and outputting data for one pixel of said stored video image during each cyce of said clock signal;
• said reading step reading the data stored in the memory module at a first predefined rate when said selection signal denotes that said video image is a monochrome image, and reading said stored data at a second predefined rate when said selection signal denotes that said video image is a color image;
• whereby said selection signal determines the mode of operation of said video memory system and the rate at which data is read from said memory module.