Terms of RAM

What Does The terms of RAM?

So many names and specific terms used in RAM. Sometimes it can be confusing. But it does not matter, after you read the following brief explanation. It can be used as a guide, at least to read the specifications and take into account the ability of the product concerned.

Speed

Speed ​​or velocity, is increasingly becoming an important factor in the selection of a memory module. CPU speed increases, coupled with the development of the use of dual-core processors, making the RAM should have a faster ability to serve the CPU.

There are several important parameters which will affect the speed of a memory.

Megahertz

The use of this term, beginning in the era of the triumph of SDRAM. Memory speeds, ranging expressed in megahertz (MHz). And still used, even to the DDR2.

Calculation based on the time interval (period) is needed between each clock cycle. Usually in the order of nanosecond time. As an example in the memory with the actual clock speed of 133 MHz, would require 8ns access time for one clock cycle.

Then shifted by the presence of DDR SDRAM (Double Information Rate). With a major development in the ability to send information over twice as much. DDR send information twice in one clock cycle.

Most products begin using effective clock speed, the result of multiplying two times the information that is sent. These are more accurately referred to as DDR Rating.

The same thing happened to DDR2. Is the result of the development of the DDR. With the main advantages of low voltage power supply that reduces heat during operation. DDR2 memory chip capacity also increased dramatically, enabling a DDR2 chip has a capacity of up to three GB. DDR2 also increased the speed compared to DDR.

PC Rating

In DDR modules, often found in terms such as PC3200. For the DDR2 module, PC2-3200. Where did this figure come from?

Commonly known as PC Rating for DDR and DDR2 modules. As this example is a DDR module with a clock speed of 200 MHz. Or for DDR rating called DDR400. With 64-bit bus width, then the information that can be transferred is 25 600 megabits per second (= 400 MHz x 64-bit). With one byte = 8 bits, then rounded to two.200MBps (Mebabyte per second). Throughput figure is used as the value of the PC rating. Additional figures ³ A2A, both on the PC Rating Rating maupu DDR, only to tell the difference between DDR and DDR2.

CAS Latency

Acronym derived from the abbreviation CAS column address strobe or column address select. Meaning they are the same, namely the specific location of an array of information on DRAM modules.

CAS Latency, or also commonly abbreviated CL, is the amount of time required (in units of clock cycles) during the delay time between the information request sent to the memory controller for the read, until the memory module successfully remove the information output. The lower the CL specification owned a RAM module, with the same clock speed, will result in faster memory access.

Peak Bandwith

Here you see the maximal peak bandwidth of the widely known RAM types. The figures illustrates the absolutely maximal transfer from RAM to the L2-cache - in peaks, not as continuously transferred.

RAM type	Max. peak bandwidth
FPM	176 MB/sec
EDO	264 MB/sec
SD	528 MB/sec