S25FS064S 64Mbit (8Mbyte) 1.8V FS-S Flash Infineon Technologies S25FS064S 64Mbit (8Mbyte) 1.8V FS-S Flash connects to a host system via a Serial Peripheral Interface (SPI). Traditional SPI single-bit serial input and output (Single I/O or SIO) are supported. Also supported are optional two-bit (Dual I/O or DIO) and four-bit wide Quad I/O (QIO) Quad Peripheral Interface (QPI) commands.