Abstract: A controller for asynchronous configurable FIFO (first-in-first-out) memory includes, in addition to two binary counters for the read pointer and write pointer, two Gray code counters for determining whether the FIFO is full or empty by a comparison of the read pointer and write pointer values expressed in Gray code. The Gray code counters avoid the problem of asynchronicity of read and write signals. The Gray code counters determine if the FIFO is full or empty depending on whether the pointer values match (indicating empty) or differ in accordance with particular Gray code patterns (indicating full). The Gray code counters each have an extra bit which allows determination of the full or empty condition from a straightforward comparison of the read pointer and write pointer values, while the Gray code eliminates the problem of multiple bit transition providing an incorrect indication of the pointer location.