As far as I know, Netac owns the patent of “USB flash drive”, but it does not own the patent of USB flash memory or USB storage. Just like “WeChat” is a registered trademark of Sony. As long as other manufacturers don’t use the name “USB Disk”, they don’t have to pay Netac. Netac was quite popular when flash drives first became popular. Objectively speaking, Netac’s things are of good quality. I still have Netac’s 32M USB flash drive. However, Netac’s prices have always been relatively expensive. Competitive. Regardless of the industry, the ultimate enterprise must rely on scale to reduce costs. Luo proposed the U disk to survive, limited to the non-replicable service for independent customers, the example he gave is nothing but garbage collection and floor tiles; An enterprise may not even be able to support a high-level manager. It can be said that it is a so-called “small and beautiful” enterprise. I rely on this professional knowledge to answer one before Zhihu Silicon Engineering Group arrives at the scene. This question essentially asks the difference in principle between Volatile Memory and non-volatile memory. Generally speaking, the principle of volatile memory is relatively simple, while the principle of non-volatile memory is diverse. Fortunately, the subject only asked Flash. I was lazy and only answered Flash. The two most widely used volatile memories are static (Static) and dynamic (Dynamic) random access memory (Random Access Memory), commonly used abbreviations are SRAM and DRAM. It is easy to see that the principle of DRAM is the so-called lossy reading: if there is electricity in the capacitor when reading, it will consume the electricity in the capacitor; if the capacitor is empty, the residual charge at the input will also be injected into the capacitor. Therefore, if the DRAM is read several times, the power stored in it will tend to the middle value, and the information is not clear. At this time, the U disk factory needs the control circuit to refresh the capacitor regularly and pull it back to the corresponding high and low level. The so-called “dynamic” of DRAM refers to the need for this refresh.