Abstract: An improved display system which includes a central processing unit (CPU) coupled to a display utilizing vertical blanking intervals. A frame buffer memory is coupled to the CPU for storing data representative of color indices for each display pixel. The frame buffer is further coupled to look-up tables (LUTs) for storing color values which are provided through digital/analog converters (DACs) to the display. The CPU updates the contents of the frame buffer and/or LUTs during the vertical blanking interval of the display. A "first half" status flag is provided to the CPU at the beginning of each vertical blanking interval. This status flag remains true until one half of the period has elapsed. A "too late" status flag is also provided at the initiation of the interval which remains low until the end of the vertical blanking interval.