For this next section, we created a custom animation that can be found in our above-embedded video. That may assist in better understanding the below definitions. Activate : opens a row of a bank. A row must be active for reading and writing data.
Precharge : closes the open row in one or all banks two separate commands , putting them into the idle state. Data is still stored in idle banks, but they must be activated again before reading or writing.
Read and Write : self explanatory. With these commands, an Auto Precharge flag can be set to automatically precharge the row when done. It can be a recurring command, but not frequently enough to make the related timings important to us. Refresh : refreshes the charge in memory cells by writing data back in place without changing it. All banks must be idle precharged before a refresh. Timings are generally divided into three categories: Primary, Secondary, and Tertiary.
Primary is the broadest, the rated settings are listed on the box e. Secondary are non-primary timings that can optionally be set in SPD see next section.
Their names and definitions will be covered in a future article. That last paragraph requires some additional explanation. They are responsible for standardizing and defining everything in this article, from abbreviations to the entire concept of DDR4. When a newly-built system is powered on for the first time, the board will check SPD and default to the best set of these JEDEC approved slow-but-safe speeds.
Even if memory manufacturers wanted to go deeper, there is a specific and limited list of SPD entries. Enabling XMP and calling it a day generally does a good enough job.
Think of a memory chip as a game of Battleship. Clearly, the lower the number the better, as in order to access the requested data both the row and the column needs to be accessed. RAS Precharge Aka tRP Example timing: 11 After a successful data retrieval from the memory, the row that was used to access the data needs to be closed. This needs to happen so that a new row can be accessed.
RAS Precharge is the time between the command is issued to close the row, and a new row becoming available for use. This has a reduced effect on performance than that of CL.
Example timing: 2 The time taken from the memory being activated to the possibility of an action being delivered to it. Neither Crucial nor Micron Technology, Inc. All other trademarks and service marks are the property of their respective owners. Find a product Part no. Your search did not match any active Crucial part numbers or configuration IDs. Find articles and site content Enter keywords. What are memory timings? CL tRCD tRP tRAS This is the time it takes for a memory module to have data ready upon request of the memory controller The time it takes to read memory after the memory is ready The time it takes for memory to have a new row ready for using data Minimum time required for a row to be active to ensure data can be accessed from it.
The time it takes to read memory after the memory is ready. The time it takes for memory to have a new row ready for using data. Minimum time required for a row to be active to ensure data can be accessed from it.
0コメント