Facts | Computer Memory Hierarchy




Facts | Computer Memory Hierarchy

Today we talk about a place that is in your digital device, each kind of memory. Memory that we now consider is referred computer, although applicable not only to a PC but also to other digital devices. It is including on mobile devices: smartphones and tablets, which are essentially computers. The memory is used to store data and is of several types. Some types of memory are used interchangeably. Others are used to perform completely different problems. Let us illustrate with a simple example written. And the memory and the processor cache and flash card for your smartphone are computer memory, although at first sight between them is not so much in common. About the memory system of the new game console, Xbox One, we recently talked in some detail. Although the game console in front of us, her memory is fully computer.

Which is computer memory and which devices it is used?

Компьютерная память

All types of computer memory can be divided into two broad categories. Volatile and nonvolatile memory. Volatile memory loses all data in the system is turned off. This is because such memory requires a constant energy supply, and as soon as the electricity supply is stopped, it ceases to function. Nonvolatile memory retains data regardless of whether the your computer or not. For example, most types of RAM are volatile categories.

The most prominent representatives of this category of non-volatile ROM (read-only memory) and flash memory, has recently received considerable spread. In particular, memory cards, CompactFlash and SmartMedia.

First of all, a list of the main types of computer memory, and only then begin to consider them:

Memory. The RAM. RAM, RAM
Permanent memory. Permanent storage device. ROM, ROM
Cache memory, Cache
Dynamic random access memory. Dynamic RAM, DRAM
Static RAM. Static RAM, SRAM
Flash memory, Flash memory
Memory type Memory Sticks in the form of memory cards for digital cameras
Virtual memory, Virtual memory
Video Memory, Video memory
Basic input / output system, BSVV, BIOS

As we have already mentioned, the memory is used not only in computers, but also for other digital devices. Those “computer-like” devices, which for convenience of presentation, we assume computers are not being distracted by the constant discussion of the differences between them. In particular, tablets, many analysts refer to computers. We are talking about including:

Game consoles
Car radio
Digital media players

Before discussing how to operate each kind of memory pointeresuemsya how it operates in general.
The hierarchical pyramid of computer memory

Иерархическая пирамида компьютерной памяти

From a technical point of view, the computer memory is any electronic storage device. Fast data loggers are used for temporary storage of information, which should be “at hand” in the processor. If the processor of your computer for any information he would handle the hard drive, the computer would run very slowly. Therefore, the information is temporarily stored in the memory to which the processor can access a higher speed.

There is a hierarchy of computer memory. Place a certain type of memory in it is its “distance” from the processor. The “closer” or that the memory for the processor, so it is generally faster. Before us is a hierarchical pyramid of computer memory that deserves a closer look.

The top of the pyramid is the processor register.
This is followed by the first cache memory (L1)
and a second level (L2)
Memory is divided into:
physical and virtual
And the cache and RAM is temporary storage of information
Next come the permanent repository of information:
ROM / BIOS; removable drives, remote devices (local area network) hard drive
The foot of the pyramid form input devices, which include:
keyboard, mouse, connected media devices; scanner / camera / microphone / video, remote sources, other sources

The processor accesses the memory according to its place in the hierarchy. The information comes from the hard drive or input device (such as a keyboard) into RAM. The processor stores the data segments, which need quick access to the cache memory. In a register contains special instructions. To consideration of cache memory and a processor register, we’ll be back.
The role of memory in general, “orchestra” of the computer

Компьютерная память

Computer work should be seen as a “band”. “Musicians” it is all the software and hardware components, including the CPU, hard drive, and the operating system that performs as well known to our readers, five major unseen problems. RAM, which is often referred to simply as “memory” is among the most important components of your computer. From the moment you turn on the computer and up to the moment when you unplug it, the processor will continuously access the memory. Let’s look at a typical scenario for any computer.

You turn on the computer. He, in turn, loaded data from the volatile memory (ROM), and began a self-test when the (power-on self-test, POST). Computer checks itself and determines whether it is serviceable and ready for a new labor session. The purpose of this phase is to ensure that all major components of the system are working properly. During the self-test, the memory controller via a fast read / write checks all the memory cells in the presence or absence of errors. The verification process is as follows: bits of information stored in memory at a certain address, and then read from there.

The computer boots from the ROM basic input-output, better known by the English acronym BIOS. In this “BIOS” provides basic information about the drives, boot order, security, automatic detection devices (Plug and Play) and some other information.

Then comes the operating system. It is loaded into memory from the hard disk (usually in a modern computer, all this is so, but other scenarios are possible.) Important components of the operating system are usually found in the computer’s memory at all times to work with him. This gives the central processing unit to immediate access to the operating system, which improves the performance and functionality of your entire computer.

When you open the application, it is written into the same memory. The volume of this type of memory these days, though large, but it is still significantly inferior to hard drive capacity. In order to save memory applications write to her only its essential components, and other “dynamically loaded” with the hard drive as needed. Each file that is loaded by a running application, also written into the RAM.

What happens when you save the file and close the application? The file is written to the hard disk, and application “pushed out” of RAM. That is, the application itself and the associated files are deleted from memory. Thus makes room for new information: other applications and files. If the modified file is not saved before the removal of the temporary storage facility, all changes will be lost.

From the above it follows that every time something is loaded or opened, it is placed in the memory, that is, the temporary storage of data. CPU easier to access information from this repository. CPU requests from memory it needs to process data calculations.

All this sounds a bit dry and did not give a complete picture of the magnitude of events. But the truly impressive looks that in modern computers exchange information between the CPU and RAM performed millions of times per second.

But memories are not limited to only one RAM. Now that we know the place of each type of memory in the overall picture of today’s digital devices, it remains to consider other types of storage media. And so …

To be continued

According to the materials computer.howstuffworks.
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Tags: memory modules , RAM , Flash memory .

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