This 80-bit active-element memory is a monolithic Schottky-clamped transistor-transistor logic (STTL) array organized as 16 words by 5 bits. A memory system using the SN74S225 easily can be expanded in multiples of 48 words or of 10 bits as shown in Figure 3. The 3-state outputs controlled by a single output-enable (OE\) input make bus connection and multiplexing easy.

A first-in, first-out (FIFO) memory is a storage device that allows data to be written into and read from its array at independent data rates. This FIFO is designed to process data at rates from dc to 10MHz in a bit-parallel format, word by word.

Reading or writing is done independently, utilizing separate asynchronous data clocks. Data can be written into the array on the low-to-high transition of either load-clock (CLKA, CLKB) input.