All they know more or less hearsay, but few know what the history of RAM and what his real function. Let’s find out together
It is one of the fundamental components of the computer, although very often is put a little overshadowed by other players as CPU, motherboard and video card. Yet we must never forget that one of the key elements of the so-called Von Neumann machine, the foundation on which theoretically also the current home computers, it is the RAM, which is the random access memory (Random Access Memory in English).
What is random access memory
The RAM memory is, how it was conceived in its historical evolution and the job functions, a space in which the computer is able to store and retrieve the data it needs to perform its functions in a short time. To constantly ensure a very high level of performance, the RAM memories work only in the moment in which they are fed electrical energy: the data, therefore, remain in the memory until the power is on. Therefore, at the time when the computer is turned off, the memory itself loses all information, emptying completely.
What is the RAM
The RAM has the task of quickly storing the data that then must be processed by the central unit of the computer, or by the Central Processing Unit processor as the CPU (acronym). In this case, do not be confused: the functions performed by the RAM memory are completely different than those of the hard drive. Both, in fact, store and retain data, but for different purposes. A magnetic hard disk drives (those drives, for instance) has access times and times of much higher than those of the processor operation reading and writing: if there was a buffer to harmonize the operation of these two components, the computer would work much slower. For example, if only to open a text file saved previously, our PC would take a number of seconds, even dozens, depending on the size of the file and the quality of available hard disk.
RAM performs exactly this task: taking performance slightly lower than the CPU, retrieves and stores data from the hard drive and gives them fed to the CPU when they are to be processed. The higher the amount of data that the RAM can store, more expediently operate the computer. In recent years, to further speed up these processes, hardware components manufacturers have developed technologies that allow hard drives to work with speeds similar to those of RAM, but managed to retain data in memory even without power supply. Hard drives solid state (Solid state disk, abbreviated as SSD) reduce the access time, reading and writing data, increasing appreciably the speed and performance of the personal computer.
The story of RAM
RAM memories are rooted in the “prehistory” of computing. As an organic form of a computer are theorized by John Von Neumann in the second half of the 40s, but the first practical realization of the theory set by the mathematician and computer American of Hungarian origin is represented by the Williams tube.
It is a cathode ray tube which, by exploiting the phenomenon of luminous persistence, allows to store data in binary format electrically (if, in a given point of the tube, the point of light was turned on the assumed value was 1, otherwise 0). Compared to their predecessors, the Williams tube ensures a marked improvement in terms of writing and data reading speed. Each tube allows to store between 512 and 1024 bits of data that, with the evolution of information technology, soon became insufficient for any type of operation.
Soon the Williams tubes are replaced by magnetic core memories that, in turn, gave way to memories printed on chips since the mid 70s. Basic, in this passage, it was the work of Robert H. Dennard, who in 1968 invented the Dynamic Random Access Memory (DRAM), become very quickly the global standard. With the passage of time, the DRAM were also placed side by side the SRAM memories (Static Random Access Memory). From a point of view totally theoretical, the latter allow to maintain the data in memory for infinite time (or at least all the time in which they are electrically powered), have low reading times and consume less. The construction costs, however, are much higher compared to DRAM and therefore are much less widely used DRAM.
For years, the standard of reference is represented by the SDRAM (acronym for Synchronous Dynamic Random Access Memory), which allow to reduce the read and write times of the data required by the normal DRAM modules. Thanks to the existence of a clock (a kind of internal metronome, able to harmonize the timing of reading and writing of the RAM to the processor), the SDRAM memories are up to three times faster than normal DRAM. The SDRAM has been a further evolution over the years, whose last stage is represented by the very recent memories DDR4 SDRAM (where DDR stands for double date rate), launched in 2011 by Samsung.
The evolution of the RAM
As seen from the 50s to today working memory has undergone many changes both from the physical point of view it is theoretical, failing to reach performance levels and certainly unimaginable workload even for the same Von Neumann. Today the most advanced RAM (the aforementioned SDRAM DDR4, which recently have replaced the now “older” DDR3) are capable of storing up to 16 gigabytes of data per module with data rates ranging from 800 megabits per second up to 1.5 gigabits per second.
On the laptop, however, is devoted to SO-DIMMs (acronym for small outline dual in-line memory module), the size of memory modules smaller than usual. The reason for this difference is also obvious: the components of a portable computer are miniaturized compared to those of a desktop computer: true for the hard drive, that is for the motherboard, that is for your video card, and also the main memory modules. They are no exception.