Since a virtual address is encoded by such a word, the most important system parameter determined by the word size is the maximum size of the virtual address space.

32位系统最大支持内存是4G。
2³⁰ = 1GB
2³² = 4GB

那么64位能支持多少呢？

2⁴⁰ = 1TB
2⁵⁰ = 1PB
2⁶⁰ = 1EB
2⁶⁴ = 16EB
我擦好吓人~ 没想到有这么多~