What is the main difference between main memory and external memory?

The main differences between main memory and external memory are physical characteristics, access speed, capacity, cost and usage. Detailed introduction: 1. Physical characteristics. Main memory is a storage device in a computer system that directly exchanges data with the CPU. It is usually composed of chips made of semiconductor materials. It is located on the computer motherboard and transmits data with the CPU through a high-speed bus. , External memory is a device for long-term storage of data in a computer system. It is usually connected to the computer through an interface and used as an external device; 2. Access speed, the access speed of main memory is very fast, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Main memory (main memory) and external memory (external memory) are two different storage devices in computer systems. They have major differences in physical characteristics, access speed, capacity, cost and usage methods. .

1. Physical characteristics:

Main memory is a storage device in a computer system that directly exchanges data with the CPU. It is usually composed of chips made of semiconductor materials, such as dynamic random access memory (DRAM). ) or static random access memory (SRAM). It is located on the computer motherboard and transmits data with the CPU through a high-speed bus.

External memory is a device used for long-term storage of data in a computer system, such as hard drives, solid-state drives, optical disks, tapes, etc. They are usually connected to the computer through interfaces (such as SATA, USB) and used as external devices.

2. Access speed:

The access speed of the main memory is very fast, because it directly transmits data with the CPU through a high-speed bus, and can complete the data in nanoseconds. Read and write.

The access speed of external memory is relatively slow because it usually requires data transmission with the computer through the interface and controller. This process takes more time, usually measured in milliseconds or longer. .

3. Capacity:

The capacity of main memory is usually limited, generally between a few GB and dozens of GB. Although the main memory capacity of some servers or high-end computers can reach several TB, But still relatively small.

The capacity of external memory is usually relatively large, ranging from a few GB to several TB, or even larger. This makes external memory ideal for long-term storage of large amounts of data.

4. Cost:

The cost of main memory is relatively high because it is made of high-speed, high-performance semiconductor materials and has limited capacity.

The cost of external memory is relatively low because it uses relatively cheap storage media, such as hard drives, optical disks, etc., and has a large capacity.

5. How to use:

Main memory is usually used to store programs and data currently being executed. It is the main target of the CPU for read and write operations. The data in main memory is lost when the computer is powered off, so it can only be used as temporary storage.

External memory is used to store data for a long time and can be saved after power failure. It can be used to store various data such as operating systems, applications, documents, multimedia files, etc.

To sum up, there are major differences between main memory and external memory in terms of physical characteristics, access speed, capacity, cost and usage. Main memory is a high-speed storage device in a computer system that directly exchanges data with the CPU. It has a small capacity, fast speed, and high cost. It is used to store currently executing programs and data. External memory is a device used to store data for a long time. It has a larger capacity, slower speed, and lower cost. It is used to save various data such as operating systems, applications, documents, and multimedia files. The two play different roles in the computer system, complement each other, and together form a complete storage system.

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