ESDRAM (Enhanced Synchronous DRAM), made by Enhanced Memory Systems, includes a small static RAM in the SDRAM chip. This means that many accesses will be from the faster SRAM. In case the SRAM doesn't have the data, there is a wide bus between the SRAM and the SDRAM because they are on the same chip. ESDRAM is the synchronous version of Enhanced Memory Systems's EDRAM architecture. Both EDRAM and ESDRAM devices are in the category of cache DRAM and are used mainly for L1 and L2 .