FIFO
FIFO memories are commonly used to organize data buffers, where the oldest (first) entry, or 'head' of the queue, is processed first. Usually FIFO ICs have two independent interfaces to read and write data to it, both interfaces may run on it’s own clock. FIFOs can have flags to indicate empty and full conditions, a half-full flag and a programmable almost-full/almost-empty flag.
FIFO memory is a storage device that allows data to be read from its array in the same order it is written
