# How does the RAM of your computer?

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2020-03-18 19:40:15

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Any data in the computer — it's zeros and ones. The text you are reading right now, has transferred from our server directly to your computer and recorded in memory — it is a sequence of ones and zeros. Right now you are looking at your monitor, which consists of pixels and displays our website. Picture — this is also ones and zeros. Video — it's ones and zeros. Music — ones and zeros. Any of the content available on your computer can be presented in the form of zeros and ones. But how?

Should start with the fact that a computer understands only binary number system. In life we use decimal because we have 10 fingers and it is simply more convenient, but the computer does not have 10 fingers — he can only work with logical devices, which only work in two States — on or off, there is a supply or not supply current. If the logical device is active, then the current supply is and the bit is equal to one if the power supply does not, then the bit is zero. Bit — it is the smallest unit of measurement. 1 bit can have only two States 1 and 0. 1 byte — it is 8 bit. Thus, if you go through all the possible combinations of zeros and ones, we get that 1 byte can store 256 combinations of bits or 2 to the power of 8. For example, «0000001», «0000010» or «10110010» — any letter of the English alphabet can be represented in a 8 bits (1 byte).

Binary code like this!

Due to the different encodings we can represent any information binary. The same applies to our programs written in different programming languages. To start any program, it must be compiled into binary code. Thus, in the binary form it is possible to represent both data and instructions (code) to work with these data. There are also interpreted languages (JavaScript, Python), in this case, the interpreter during the execution of the program analyzes the code and compiles it into a language understood by our computer, that is, a sequence of zeros and ones, and in this case there is no need to compile the program each time you wish to run it.

## How does the CPU?

We can't talk about memory without saying a few words about the processor. The CPU and RAM are quite similar, as both involve a logical unit that can take only two States. However, the CPU performs tasks associated with computing. For this he has a device control — it received our instructions, arithmetic logic unit — it is responsible for all arithmetic operations (addition, subtraction, and so on) and registers.

Since the instructions entering the processor work with data from memory, these data need to be stored somewhere. To take them constantly from RAM — for too long, so the processor has its own memory, presented in the form of several registers — it is the fastest memory in the computer.

What is the register? A register in the processor is presented in the form of a trigger, which can store 1 bit of information. The trigger — this is one of many logic elements in microchips. Thanks to its logic, it is able to store information. Here is the D-trigger:

This is D-trigger and it is capable of storing information. Every simple logical device, including D-flip-flop consists of logical operations. In the photo above you can see the sign «&» — it is logical And

the truth table for the logical «And»

Top switch «D» in the D-trigger changes the value of the bit, and the bottom «C» enables or disables storage. You must be wondering how this "D-latch". The more triggers you can explore on video below:

In Addition to the D-flip-flop, there are also RS-flip-flop, JK flip-flop and others. This topic is not one book can learn logic device of microchips themselves. It would be nice because obviously .

## what is RAM?

Now back to our memory, it is a big group of registers that store data. There is SRAM (static RAM) and DRAM (dynamic memory). In a static memory registers provided in the form of triggers, and dynamic in the form of capacitors, which may eventually lose charge. Today RAM used DRAM, where each cell — is a transistor and a capacitor, which in the absence of power loses all data. That's why, when we turn off the computer, cleared. All drivers and other important programs the computer in the off state keeps on the SSD, and even when enabled, it puts the necessary data into memory.

A cell of the dynamic RAM, as mentioned above, consists of a capacitor and a transistor, it stores 1 bit of information. More precisely, the information itself keeps the capacitor and for switching the state is responsible for the transistor. Condenser we can produce in the form of a small bucket, which is filled with electrons atthe flow of current. Read more the work of the dynamic RAM . Since then, little has changed in how it works. If the capacitor is filled with electrons, its state is equal to unity, i.e. the output has 1 bit of information. If not, then zero.

## How the computer saves data in RAM?

A Sequence of bits or 1 byte «01000001», recorded in the RAM, could mean anything — it could be a number «65», the letter «And» or the color of the picture. Ensure that the operating system can understand what these bits were designed different encodings for different data types: MP3, MPEG4, WAV, ASCII, Unicode, BMP, Jpeg. For example, let's try to write the Cyrillic letter «R» in our memory. For this you first need to convert it to a Unicode character (hexadecimal number). "R" in the Unicode table is "0440". Next, we need to choose which encoding will preserve the number, let it be UTF-16. Then in the binary system Unicode symbol takes the form «00000100 01000000». And already this value we can write in RAM. It consists of two bytes. But if we took English «s» in binary it would look like this «01110011».

The fact that the English alphabet is only 1 byte as in UTF-encoding it fits in the range of numbers from 0 to 255. In 256 combinations calmly fit the numbers 0 to 9 and the English alphabet, but other symbols are already there, so, for example, Russian characters have 2 bytes and Japanese or Chinese characters, we will need 3 or even 4 bytes.

So we figured out how memory works and how you can write data to it. Liked the material? Share it with your friends and let's discuss it .

RAM — it's a complex device, and know his work will be helpful to everyone

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