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Because system performance depends on how fast memory can be used, this timing directly affects the performance of the system. The timing of modern synchronous dynamic random-access memory (SDRAM) is commonly indicated using four parameters: CL , T RCD , T RP , and T RAS in units of clock cycles ; they are commonly written as four numbers ...
Memory bandwidth is the rate at which data can be read from or stored into a semiconductor memory by a processor. Memory bandwidth is usually expressed in units of bytes/second , though this can vary for systems with natural data sizes that are not a multiple of the commonly used 8-bit bytes.
The gap between processor speed and main memory speed has grown exponentially. Until 2001–05, CPU speed, as measured by clock frequency, grew annually by 55%, whereas memory speed only grew by 7%. [1] This problem is known as the memory wall. The motivation for a cache and its hierarchy is to bridge this speed gap and overcome the memory wall.
Associated with speed, the more RAM there is in the system, the faster the computer can run, because it allows the RAM to run more information through to the computer's (CPU). Not only does adding more RAM to a computer help it run faster, it helps boots up a computer immensely faster compared to booting up a system with less RAM.
Synchronous memory interface is much faster as access time can be significantly reduced by employing pipeline architecture. Furthermore, as DRAM is much cheaper than SRAM, SRAM is often replaced by DRAM, especially in the case when a large volume of data is required. SRAM memory is, however, much faster for random (not block / burst) access.
Because memory modules have multiple internal banks, and data can be output from one during access latency for another, the output pins can be kept 100% busy regardless of the CAS latency through pipelining; the maximum attainable bandwidth is determined solely by the clock speed.
The operating system will place actively used data in RAM, which is much faster than hard disks. When the amount of RAM is not sufficient to run all the current programs, it can result in a situation where the computer spends more time moving data from RAM to disk and back than it does accomplishing tasks; this is known as thrashing.
RAM drives can access data with only the address, eliminating this latency. Second, the maximum throughput of a RAM drive is limited by the speed of the RAM, the data bus, and the CPU of the computer. Other forms of storage media are further limited by the speed of the storage bus, such as IDE (PATA), SATA, USB or FireWire. Compounding this ...