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This driver provides support for four kinds of memory backed virtual disks: malloc, preload, vnode, swap. Disks may be created with the next command line tools: mdconfig and mdmfs. An example of how to use these programs follows. [3] To create and mount memory disk with mdmfs: # mdmfs -F newimage -s 5m md0 /mnt
DDR SDRAM operating with a 100 MHz clock is called DDR-200 (after its 200 MT/s data transfer rate), and a 64-bit (8-byte) wide DIMM operated at that data rate is called PC-1600, after its 1600 MB/s peak (theoretical) bandwidth. Likewise, 12.8 GB/s transfer rate DDR3-1600 is called PC3-12800. Some examples of popular designations of DDR modules:
Double data rate (DDR) memory controllers are used to drive DDR SDRAM, where data is transferred on both rising and falling edges of the system's memory clock.DDR memory controllers are significantly more complicated when compared to single data rate controllers, [citation needed] but they allow for twice the data to be transferred without increasing the memory's clock rate or bus width.
In computing, serial presence detect (SPD) is a standardized way to automatically access information about a memory module.Earlier 72-pin SIMMs included five pins that provided five bits of parallel presence detect (PPD) data, but the 168-pin DIMM standard changed to a serial presence detect to encode more information.
In Windows 3.1 and Windows 9x, there is also a command-line loadable version of HIMEM.SYS called XMSMMGR.EXE. It can load extended memory services after the system boots into the command prompt. It can load extended memory services after the system boots into the command prompt.
DDR SDRAM employs prefetch architecture to allow quick and easy access to multiple data words located on a common physical row in the memory. The prefetch architecture takes advantage of the specific characteristics of memory accesses to DRAM. Typical DRAM memory operations involve three phases: bitline precharge, row access, column access. Row ...
The time to read the first bit of memory from a DRAM without an active row is T RCD + CL. Row Precharge Time T RP: The minimum number of clock cycles required between issuing the precharge command and opening the next row. The time to read the first bit of memory from a DRAM with the wrong row open is T RP + T RCD + CL. Row Active Time T RAS
A memory rank is a set of DRAM chips connected to the same chip select, which are therefore accessed simultaneously. In practice all DRAM chips share all of the other command and control signals, and only the chip select pins for each rank are separate (the data pins are shared across ranks).