Implementing application specific memory

Successful realization of application specific memory devices (ASM) requires designing onto existing standard ASIC or memory processes, at least in the short term, to avoid the cost and time penalties of developing new processes. Existing memory and ASIC processes have been optimized independently so there are well-recognized problems in seeking to combine memory and logic on a single chip. A number of applications demanding such a combination are emerging that warrant the design effort to overcome such problems. While processes better-suited to mixed memory and logic will become more generally available, the designer of an ASM today generally must find a way to add higher-density memory onto an ASIC chip, or, if a still greater capacity is needed, add efficient logic to a DRAM process. Neither task is as easy as it may seem.