 Counting from least to most significant bit, an attribute byte dedicates three bits for the foreground colour, three bits for the background colour, one bit for the bright flag, and one bit for the flashing effect (which causes the video display to alternate foreground and background colours periodically).BRIGHT BLACK colour was not in all models of ZX Spectrum and ZX Spectrum Emulators (but it is possible to regulate the palette in several emulators (ex.EmuZWin, ZX Spin), including bright black).