1. Function and orientation

As a cache between CPU and external memory (such as hard disk), it solves the problem of mismatch between CPU operation speed and external memory reading and writing speed. All programs need to be loaded into the memory before running, and the CPU reads instructions and data directly from the memory.

2. Development process Early stage: SIMM (Single Contact Memory Module) is the main memory in the early stage, such as 30pin and 72pin specifications, which need to be used in pairs, with small capacity and slow speed. Sdram era: synchronous technology is introduced to work synchronously with CPU external frequency, and single channel/dual channel design improves bandwidth, such as PC100 and PC133. DDR Series: Support double data rates (DDR, DDR2, DDR3, DDR4, DDR5), greatly increase frequency and capacity, and reduce power consumption.