We will analyze volatile memory (that loses the data once our PC is no longer fed): the Random Access Memory (RAM – http://www.abbreviationfinder.org/acronyms/ram.html).
RAM is temporary memory that contains programs and data that are processed by the processor, able both to be read or written. It is a very fast memory which guarantees the same speed of access to any memory address, and uses a solid state technology.
The RAM has a great influence on the performance of a system. It is a memory access times much faster than mass storage. If the processor were to communicate directly with mass storage devices to retrieve the data to be processed, the processing time would be long. The RAM is interposed between the CPU and memory which collects information that the processor must process, thus avoiding excessive wait times. Once processed, the CPU returns values to the RAM that will provide it to mass storage. If, during the execution of a program, the availability of RAM should run low, the CPU can still use mass memory (paging file), but slowing down the whole system.
The RAM to be installed, are welded on memory (commonly called “RAM bars”). The formats most commonly used memory module DIMM (for desktop computers) and the smallest version SODIMM (used mainly for laptops). A RAM module can be single-sided (which contain the RAM on one side of the bar) or double-sided (on both sides).
Modern RAM are “synchronous”: This means that, in order to cooperate with the CPU, the RAM will sync with the memory bus (i.e. the path that the data they accomplish between CPU and memory) using the clock, which marks the time of exchange.
The first synchronous memories were the SDRAM, then replaced by the DDR (with twice as fast to an SDRAM). Further improvements in performance and power consumption is obtained thanks to the new DDR2, DDR3 and DDR4. It must be remembered that no DDR technology is compatible with the other.
The parameters that characterize a RAM are the Transfer Rate (calculated in MB/s and indicating the peak speed of data transfer) and Front Side Bus speed (calculated MHz memory bus frequency shows that supports).
RAM is one of the most important elements of a PC. Just remember that when you buy a RAM module, make sure that it works like form factor with the motherboard and that it is supported by the chipset.