In summary, Winbond's W25X and W25Q SpiFlash® Multi-I/O Memories feature the Serial Peripheral Interface (SPI), densities from 1 M to 128 M-bit, small erasable sectors and one of the industry's highest performance levels. The W25X family supports Dual-SPI effectively doubling standard SPI clock rates. The W25Q family is a "superset" of the 25X family with Dual-I/O and Quad-I/O SPI for even higher performance. Clock rates up to 104 MHz achieve an equivalent of 416 MHz (50 M-Byte/S transfer rate) when using Quad-SPI. This is more than eight times the performance of ordinary Serial Flash (50 MHz) and even surpasses asynchronous Parallel Flash memories while using fewer pins and less space. Faster transfer rates mean controllers can execute code (XIP) directly from the SPI interface or further improve boot time when shadowing code to RAM. Additionally, some SpiFlash devices offer the Quad Peripheral Interface (QPI) supporting true Quad Commands for improved XIP performance and simpler controller circuitry.