As we all know, the RAM memory is one of the fundamental components for proper operation of our PC, since its existence allows the computer to be started, and thus the processing of the necessary instructions for all software operating system and user applications can be executed normally.
However, what few people know is that a computer works with four different memories, used to perform various functions. These are the RAM, ROM, SRAM or cache memory and virtual memory or swap. Precisely this topic will discussed in this article.
Among them, the most important is called RAM (Random Access Memory) since our computer could not function without it. In this RAM, different types of data are stored, from the temporal processes of file modifications, to the instructions that allow the execution of applications that we have installed in our PC.
Therefore, it is constantly used by the microprocessor, which accesses it to search or temporarily store information concerning the processes performed on the computer.
Within RAMs different types of technologies exist that mainly differ in their access speed and physical form. Among them are the DRAM, SDRAM, RDRAM, among others.
The so called DRAM (Random Access Memory Dynamic), have been used in computers since the early years of the decade of the 80’s, and even today is still used. This memories are one of the cheapest, although his biggest disadvantage is related to the processing speed, as it is one of the slowest, which has led manufacturers to modify their technology to offer a better product.
As for the type of SDRAM technology, derived from the first, he began to be marketed in the late 90’s, and thanks to this type of memory, it was possible that the processes were significantly more efficient, because it can operate at the same speed as the motherboard to which it is incorporated.
Meanwhile, the RDRAM technology is one of the most expensive because of its complexity of manufacture, and they were only used on powerful computers. Currently, this type of memory is no longer manufactured.
Another difference between the various RAM is the type of module that question, which may be SIMM (Single In-line Memory Module) DIMM (Double Memory Module) and RIMM (Rambus in-line Memory Module), depending the pin count and the physical size of the module.
In addition to RAM, computers work with memory called ROM, Read Only Memory, which as its name suggests is a read-only memory, as most of these memories cannot be modified because they do not allow his writing.
The ROM is built into the motherboard and is used by the PC to start the BIOS, which is basically a program that has the instructions to guide the computer during startup operations.
Among its functions, the BIOS begins with a process called POST (Power On Self Test) during which inspect the whole system to verify that all components are working properly to begin the start.
To do this, the BIOS queries a register, in which all information about the hardware you have installed on your computer is stored, to check that everything is in order. This register is called CMOS Setup.
While we mentioned that in many cases the ROM cannot be changed, now many motherboards incorporate new models that allow for writing ROM, so that the user can make changes to the BIOS in order to improve their performance.
The fundamental difference between RAM and ROM lies in speed, since the ROM, being a sequential memory, need to go through all these records to find the information you seek, while the RAM works randomly, meaning you can access the information you want directly.
This factor makes the speed of RAM is significantly higher. Also, this capability is greater than that of the ROM, and unlike the latter, the RAM is not integrated into the motherboard, allowing the user to expand the amount of RAM your PC.
Another type of memory used by computers is called SRAM, known as cache memory. Both the processor and the hard drive and the motherboard have their own cache, which basically protects different directions that are used by the RAM to perform different functions such as running programs installed in the PC.
The task performed by the cache memory is to store to disk locations occupied by programs that have been implemented thus can access data more quickly and directly.
There are three different types of cache:
- The L1 cache located inside the processor and operates at the same speed as the latter, and in which instructions and data are stored.
- The L2 cache are usually of two types: internal and external. The first is within the motherboard, while the second is located in the processor but externally, making it slower than L1 cache.
- The L3 cache are incorporated into only some of the more advanced microprocessors, resulting in increased processing speed.
On some computers, especially those that have Microsoft Windows or Linux as operating system, also we find the so-called virtual memory or swap.
This type of memory, which works similar to the cache memory, is created by Windows or Linux to be used exclusively by the operating system. In the case of Linux is called swap memory, and is usually located on a different partition on the disk, while Microsoft system is a file within the same operating system.
In many cases the virtual memory usually produces certain problems that cause the PC to crash, because this type of memory has been created by the system in the hard drive and sometimes can exceed the capacity of process.
If run software using virtual memory, only obtain bad results, since our PC becomes more sluggish as processing speed subtracts the hard drive.
The best way to avoid this problem is to expand the amount of RAM memory of our PC, so that the system does not require the creation of additional virtual memory and thus slow down during our work processes.
With regard to this point, now there are three types of RAM, DDR, DDR2 and DDR3, these latter two still widely used, while the first and is not used by any computer manufacturer.