Easily upgradable video memory system and method

Abstract From the Canadian patent

A video memory system is disclosed in which the memory module used to store video data also generates a selection signal that indicates whether the module is a monochrome or color memory module. Memory control logic generates a pixel clock which governs the rate at which pixels of data are output to a monitor, and a load clock which determines the rate at which data is read from the memory module. The load clock is generated at a first rate when the selection signal denotes a monochrome memory module and at a second, faster rate when the selection signal denotes a color memory module. A shift register receives video data from the video memory module at the rate of the load clock and, …