The maximum amount of ram a 64bit machine can theoretically address

computer-architecture

I'm reading through my computer architecture book and I see that in an x86, 32bit CPU, the program counter is 32 bit.

So, the number of bytes it can address is 2^32 bytes, or 4GB. So it makes sense to me that most 32 bit machines limit the amount of ram to 4gb (ignoring PAE).

Am I right in assuming that a 64bit machine could theoretically address 2^64 bytes, or 16 exabytes of ram?!

Best Answer

Theoretically: 16.8 million terabytes. In practice: your computer case is a little too small to fit all that RAM.

http://en.wikipedia.org/wiki/64-bit#Limitations_of_practical_processors

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