To compete with the popular Family Computer in Japan, NEC Home Electronics launched the PC Engine in 1987, and Sega Enterprises followed suit with the Mega Drive in 1988. The two platforms were later launched in North America in 1989 as the TurboGrafx-16 and the Genesis respectively. Both systems were built on 16-bit architectures and offered improved graphics and sound over the 8-bit NES. However, it took several years for Sega's system to become successful. Nintendo executives were in no rush to design a new system, but they reconsidered when they began to see their dominance in the market slipping.
How was the 8-bit NES an improvement?