Book excerpt: DRAM is abbreviation of Dynamic Random Access Memory. DRAM is volatile memory electronic devices such as personal computer, cell phone, pad, etc. DRAM (Dynamic Random Access Memory) becomes an important component for a device is after the Bill Gates and Paul Allen found Microsoft Corporation which makes the personal computer software operation system DOS (disk operation system) in 1975. Personal computer industry is booming after Apple Incorporation and Microsoft Corporation have launched the personal computer and computer operation system to this world.