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Because the CAS latency is specified in clock cycles, and not transfers (which occur on both the rising and falling edges of the clock), it is important to ensure it is the clock rate (half of the transfer rate) which is being used to compute CAS latency times. [citation needed] Another complicating factor is the use of burst transfers.
With this 1 ns clock, a CAS latency of 7 gives an absolute CAS latency of 7 ns. Faster DDR3-2666 memory (with a 1333 MHz clock, or 0.75 ns exactly; the 1333 is rounded) may have a larger CAS latency of 9, but at a clock frequency of 1333 MHz the amount of time to wait 9 clock cycles is only 6.75 ns.
At higher clock rates, the useful CAS latency in clock cycles naturally increases. 10–15 ns is 2–3 cycles (CL2–3) of the 200 MHz clock of DDR-400 SDRAM, CL4-6 for DDR2-800, and CL8-12 for DDR3-1600. Slower clock cycles will naturally allow lower numbers of CAS latency cycles.
To be precise, EDO DRAM begins data output on the falling edge of CAS but does not disable the output when CAS rises again. Instead, it holds the current output valid (thus extending the data output time) even as the DRAM begins decoding a new column address, until either a new column's data is selected by another CAS falling edge, or the ...
Memory latency is the time (the latency) between initiating a request for a byte or word in memory until it is retrieved by a processor. If the data are not in the processor's cache , it takes longer to obtain them, as the processor will have to communicate with the external memory cells.
Latency, from a general point of view, is a time delay between the cause and the effect of some physical change in the system being observed. Lag, as it is known in gaming circles, refers to the latency between the input to a simulation and the visual or auditory response, often occurring because of network delay in online games. [1]
Three SDRAM DIMM slots on a ABIT BP6 computer motherboard. A DIMM ( Dual In-Line Memory Module ) is a popular type of memory module used in computers. It is a printed circuit board with one or both sides (front and back) holding DRAM chips and pins . [ 1 ]
The CAS-2 command is used as the second half of all commands that perform a transfer across the data bus, and provides low-order column address bits: Read commands must begin on a column address which is a multiple of 4; there is no provision for communicating a non-zero C0 or C1 address bit to the memory.