Registered memory

The term register module or English Registered modules (including R -DIMM, RDIMM, Registered memory or Registered RAM called ) refers to a variety of memory modules, which are often found in main storage server and workstation use. The aim of the technique is to use additional registers to reduce the electrical load on the memory controller, and thus to increase the number of connectable memory chips, as well as increase data integrity. The term is often incorrectly synonymous with the previous technique Buffered modules ( " buffered module " ), since the latter has similar goals.

Operation

Since the introduction of SDRAM and thus also applicable for DDR SDRAM, there are no more buffers on the modules, but register, hence the term Registered RAM. In the time before, until the era of EDO RAM, an analog technique with buffers Buffered modules was used, known. Registered memory modules have additional (usually two ) registers chips, through which the signals of the address lines are performed to reduce the electrical load on the motherboard chipset. In addition, usually there is also a PLL block which is used for processing of the clock signal and clock signal relieves the driver of the mainboard. Unregistered modules not only when the data lines of all the modules, but the address line inputs of all the memory chips are connected in parallel. In contrast, Registered modules relieve the address driver lines, so that the chipset is working stable. As a result, these modules are often organized differently. Instead of double-sided modules ( two banks ) single-sided modules are often (a bank ) used to relieve the data signal line drivers because fewer chips are connected in parallel. Registered modules are almost exclusively available as ECC version, which often leads to that the two terms are mentioned in the same breath, even though they have nothing in common.

Disadvantages

However, the technique has some disadvantages. In addition to the higher prices of the modules and a compelling need support from the motherboard, including the BIOS, latency, and thus the data throughput plays a major role. For Registered modules, the input signals appear until exactly one clock cycle later at the outputs, as is the case in normal. In addition, Registered DIMMs have a slightly different pinout than ordinary modules. To be remarked that Registered modules can not be combined with modules Unregistered. Also, registers can not disable this, as is the case with ECC. Additionally, slightly higher than usual for the Registered DIMM modules usually the power consumption.

Future

Registered memory are SDR, DDR, DDR2 and now offered for DDR3 SDRAM.