There are two ways of transmitting data, either parallel or serial. Parallel means each bit has a single wire devoted to it and all bits transmitted are at the same time. In serial mode the bits are transmitted as a series of pulses. When NOR flash was first introduced, it came with a parallel interface for maximum performance. Serial means that each bit is addressed sequentially thus making the interface simpler and smaller but the corresponding throughput is significantly slower. Fewer lines allows for dramatically smaller layouts leading to a huge advantage in cost and miniaturization, making them ideal for embedded applications. It also allows for smaller packaging since not as many I/O’s are required.