Memory classification

Brief Introduction

The storage medium that constitutes memory mainly uses semiconductor devices and magnetic materials. The smallest storage organization in memory is a bistable transistor circuit or a CMOS transistor or magnetic material storage element, which can store a binary code. A storage unit is composed of several storage elements, and then a memory is composed of many storage units.

There are several different classification methods for memory based on the performance and usage of stored data.

1. Classification by storage medium

Semiconductor memory: Memory composed of semiconductor devices. Magnetic surface memory: Memory made of magnetic materials.

2. Classification by storage pipeline

Random memory: The content of any storage unit can be randomly accessed, and the access time is independent of the physical location of the storage unit. Sequential memory: It can only be accessed in a certain order, and the access time is related to the physical location of the storage unit.

3. Classification by memory read and write function

Read Only Memory (ROM): A semiconductor memory that stores fixed and unchanging content and can only be read out but not written to. Random Read Write Memory (RAM): Semiconductor memory that can both read and write.

4. Classification by information's preservability

Non permanent memory: Memory in which information disappears after a power outage. Permanent memory: Memory that can still store information after a power outage.

5. Classification by role in computer systems

Main memory (memory): Used to store active programs and data, with high speed, small capacity, and high cost per unit. Auxiliary memory (external memory): mainly used to store inactive programs and data, with slow speed, large capacity, and low cost per unit. Buffer memory: mainly used for buffering in two components with different working speeds.