 A special case involves alternating between the two available colours per attribute cell for 4 pixels each, allowing each 4×1 region to be treated as an independently colourable 'pixel' (although the limitation of one brightness level per 8×1 cell is still in effect).ULAPlus is compatible with the standard ZX Spectrum display, if used only to modify the 16 basic colours.Yet any software that uses the full 64 colours will trigger the "flash" attributes of the original Spectrum.