Memory chips belong to general-purpose integrated circuits and are a specific application of the embedded system-on-a-chip (SoC) concept in the storage industry. Their principle is to embed software into a single chip to achieve multifunctionality, high performance, and support for various protocols, hardware, and applications. So, what are some common types of memory chips? And which are some well-known memory chip manufacturers in China?
Memory is divided into internal memory (or main memory) and external memory (or secondary storage).
Internal memory is frequently used by the computer during program execution and is directly accessible during an instruction cycle. External memory requires the computer to read information from an external storage device such as magnetic tape or a disk. This is similar to a student taking notes in class. If the student knows the content without looking at the notes, the information is stored in "internal memory." If the student needs to refer to the notes, then the information is in "external memory."
Main Memory Introduction
Main memory refers to the memory that the central processing unit (CPU) can directly access to store currently used (i.e., executing) programs and data. Physically, it consists of one or more integrated circuits with data input/output and data storage functions. Main memory is only used to temporarily store programs and data; once the power is turned off or a power outage occurs, the programs and data within it will be lost.
Since the 1970s, main memory has gradually adopted large-scale integrated circuits. The most widely used and economical type is dynamic random access memory (DRAM).
Structural composition
Typically, main memory consists of two parts: read-only memory (ROM) and random access memory (RAM).
Read-only memory (ROM) is a type of memory that can store information once written to it and can only be read thereafter. Under normal circumstances, the contents stored in ROM are relatively fixed over a long period of time, and the stored information will not disappear even when the power is off. Therefore, ROM is a non-volatile memory.
Random access memory (RAM), also known as "random access memory", allows data to be accessed randomly from a memory cell at a specified address. Before the advent of semiconductor memory, it was mainly magnetic core memory, which used a magnetic core as the storage cell.
Memory Classification
Based on the performance of the storage materials and the different methods of use, there are several different ways to classify memory.
If we categorize memory chips based on whether they retain data after the power is turned off, we can divide them into volatile memory and non-volatile memory. Volatile memory is mainly represented by Random Access Memory (RAM), with Dynamic Random Access Memory (DRAM) being the most widely used. In fact, most of the memory modules in our everyday electronic products use this type of chip.
Flash memory, also known as flash storage, combines the advantages of ROM and RAM. It not only possesses the performance of Electronically Erasable Programmable ROM (EEPROM) but also retains data even when power is off, while allowing for fast data retrieval (an advantage of NVRAM). Its applications are very wide-ranging. Currently, there are two main types of Flash memory: NOR Flash and NAND Flash.
The most common non-volatile storage technologies are NOR Flash and NAND Flash. NOR Flash has a faster read speed and is widely used as the main device for code storage. It can be found in many everyday devices such as digital set-top boxes, home gateways, automotive electronics, security monitoring, routers, and wearable devices. NAND Flash, on the other hand, has a cost advantage when it comes to high capacities, and its read and write speeds are faster than traditional magnetic and optical memories, making it the mainstream large-capacity data storage device today.
NAND Flash can be further divided into several categories: SLC, MLC, TLC, and 3D Nand. Among them, SLC can be used for network communication, voice storage, printers, industrial control, and enterprise-level storage. MLC, TLC, and 3D Nand are mainly used in mobile phones, computers, SSDs (solid-state drives), AR/VR, data centers, cloud computing, and servers.
