Bandwidth is an important parameter, but it doesn't completely define memory performance. Latency is an equally critical factor that can improve or impede performance. Turnaround latency measures the time a DRAM takes to transition from a read to a write operation or vice versa. Long transition times degrade system performance regardless of the memory bandwidth. The numbers assume no page misses.
Initial latency is the time it takes to begin the flow of data when a read or write is requested.
Because the memory device actually spends most of its time sitting idle, initial latency slows the system more frequently than turnaround latency. Solving initial latency is therefore more critical to overall system performance. Real performance numbers will depend on the system in which the memory is used, its environment and a standard performance benchmark. It is in those areas that the Rambus DRAM still has to prove itself, and soon. All rights reserved.