With the emerging huge demand for multimedia applications, even personal computers have come to require enhanced memory systems, especially for 3-D graphics, MPEG encoding, and image/ voice recognition. While the large memory bandwidth of RambusDRAMs and Synchronous DRAMs offers high-speed data transfer and large capacity, they fall short in terms of low latency. Despite the efforts made by many programmers to circumvent the effects of the high latency of DRAM access, memory access instructionscontinue to accumulate, which limit system performance. The many conditional branch/jump operations of mixed multi-media applications (e.g., MPEG-4), for example, make such attempts at circumvention almost completely impossible. In fact, both lower random access latency and larger bandwidth are actually more pressing requirements for the latest memory systems.
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