Prior to the introduction of SPIFI, in order for the CPU to use data from external serial Flash, first the CPU had to write to the control register, then the data had to be loaded into the buffer, which when completed updated the control register. The CPU then read the control register and transferred the data from the buffers into the CPU RAM. All transfers had to go through a buffer in the interface and then were transferred to RAM. Sometimes the transfer was done via DMA which is more efficient, but it was still necessary for the CPU to read the data from RAM. This traditional process of using serial Flash is complicated and slow.