LH540204

The LH540204 is a FIFO (First-In, First-Out) memory device, based on fully-static CMOS dual-port SRAM technology, capable of storing up to 4096 nine-bit words. It follows the industry-standard architecture and package pinouts for nine-bit asynchronous FIFOs. Each nine-bit LH540204 word may consist of a standard eight-bit byte, together with a parity bit or a block-marking/framing bit.

The input and output ports operate entirely independently of each other, unless the LH540204 becomes either totally full or else totally empty. Data flow at a port is initiated by asserting either of two asynchronous, assertive- LOW control inputs: Write (W) for data entry at the input port, or Read (R) for data retrieval at the output port.

Full, Half-Full, and Empty status flags monitor the extent to which the internal memory has been filled. The system may make use of these status outputs to avoid the risk of data loss, which otherwise might occur either by attempting to write additional words into an already-full LH540204, or by attempting to read additional words from an already-empty LH540204. When an LH540204 is operating in a depth-cascaded configuration, the Half-Full Flag is not available.