People who know computer must be familiar with RAM, however, the acquaintance of memory may only limits on SDRAM and DDR SDRAM, in fact, there’re many kinds of memories, from whether it’s writable, it could be divided into two types: RAM and ROM. And each type has many sub types. Next let’s take a tour to see what in the earth types of memories there are!
1. RAM (Random Access Memory)
 
The features of RAM: when starts, all running data and applications of the operation system and applications would be placed inside, besides, you can modify and read the data anytime. It needs continual power supply, once system power is off, then all data and applications stored in it would be auto erased, and it could not recover ever again.
And according to different components, RAM has 18 types:
01. DRAM (Dynamic RAM):
 
 This is most common RAM, one radio tube and one capacitor is composed to one bit storage unit. DRAM stores every memory bit as an electric charge in the storage unit, carrying storage action by capacitor’s charge/discharge. But because the capacitor has power-leak problem, so you’d have to refresh once every few seconds, otherwise data would get lost. The accessing time accords with discharging time, about 2 to 4 ms. However, as the cost is very cheap, generally, we can use it as the main storage of the computer.
02. SRAM (Static RAM)
 
Static means the data could stay in the memory for a long time, but not to read anytime. Every 6 radio tubes are composed to a bit storage unit, because there’s