Dynamic random access memory

Semiconductor memory

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synonym DRAM (DRAM) generally refers to dynamic random access memory

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Dynamic random access memory （ Dynamic Random Access Memory ， DRAM ）It is a semiconductor storage The main principle is to use the amount of charge stored in the capacitor to represent a Binary Is the bit 1 or 0. Because in reality transistor There will be Leakage current As a result, the number of charges stored on the capacitor is not enough to correctly identify the data, resulting in data corruption. Therefore, periodic charging is an unavoidable requirement for DRAM. Because of this feature, which requires periodic refresh, it is called "dynamic" memory. Relatively speaking, Static memory （ SRAM ）As long as the data is stored, the memory will not be lost even if it is not refreshed.

Chinese name: Dynamic random access memory
Foreign name: Dynamic Random Access Memory

Features: Keep data for a short time
Role: data access

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Dynamic random access memory （ Dynamic Random Access Memory ， DRAM ）It is a semiconductor storage The main principle is to use the amount of charge stored in the capacitor to represent a Binary Is the bit 1 or 0. Because in reality, transistors will have Leakage current As a result, the number of charges stored on the capacitor is not enough to correctly identify the data, resulting in data corruption. Therefore, periodic charging is an unavoidable requirement for DRAM. Because of this feature, which requires periodic refresh, it is called "dynamic" memory. Relatively speaking, Static memory （ SRAM ）As long as the data is stored, the memory will not be lost even if it is not refreshed.

Compared with SRAM, DRAM has the advantage of simple structure - Data Only one capacitor and one transistor In contrast, one bit on SRAM usually requires six transistors. Because of this, DRAM has a very high density, high capacity per unit volume and low cost. On the contrary, DRAM also has the disadvantages of slow access speed and large power consumption.

And most of the Random access memory (RAM), because the data in DRAM will disappear soon after the power is cut off, it belongs to a Volatile memory (volatile memory) equipment.^[1]

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DRAM usually uses a capacitor and a transistor Arranges a cell into a two-dimensional matrix. The basic operating mechanism is divided into read and write. When reading, let the Bitline (BL) charge to half of the operating voltage first, and then turn on the transistor to allow BL and capacitor to generate charge sharing phenomenon. If the internal stored value is 1, the BL voltage will be raised by charge sharing to half higher than the operating voltage, otherwise, if the internal stored value is 0, The BL voltage will be pulled down to less than half of the operating voltage. After the BL voltage is obtained, the internal values of 0 and 1 will be determined by the amplifier. When writing, the transistor will be turned on. If you want to write 1, the BL voltage will be raised to the operating voltage so that the capacitor will store the operating voltage. If you want to write 0, the BL will be reduced to 0 volts so that there is no charge inside the capacitor.^[1]

Random access memory

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Random access memory (English: R andom A ccess M emory， abbreviation: RAM ）, also called Main storage , is and CPU Direct data exchange Internal memory 。 It can read and write at any time (except when refreshing, see below), and is fast. It is usually used as a temporary for the operating system or other running programs data storage Media.

Main memory is the main memory inside the computer, which is used to load various programs and data for CPU Direct operation and application. Because DRAM has a high cost performance ratio and good scalability, it is an ordinary computer today Main storage The most important part of. Computer production in 2014 Main storage Mainly DDR3 SDRAM From 2016 DDR4 SDRAM Gradually popularized, Laptop Manufacturers such as ASUS and Acer Start with DDR4 Memory replaces DDR3L.^[1]

Dynamic random access memory

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brief introduction

working principle

Random access memory

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